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Fetal-Maternal Intra-action: Politics of New Placental Biologies
Abstract
Extensively employed in reproductive science, the term fetal?maternal interface describes how maternal and fetal tissues interact in the womb to produce the transient placenta, purporting a theory of pregnancy where ?mother?, ?fetus?, and ?placenta? are already-separate entities. However, considerable scientific evidence supports a different theory, which is also elaborated in feminist and new materialist literatures. Informed by interviews with placenta scientists as well as secondary sources on placental immunology and the developmental origins of health and disease, I explore evidence not of interfacing during pregnancy, but of intra-action, or the mutual emergence of entities in simultaneous practices of differentiation and connection. I argue that attending to evidence that can be figured as intra-action enables us to recognize, account for, and attend to diffuse responsibilities for fetal?maternal outcomes that extend beyond mothers to the biosocial milieus of pregnancy. In reimaging the intra-action of placentas, a new understanding of what constitutes a ?healthy pregnancy? becomes possible.
... In recent years, there was a call for a reappraisal of Medawar's paradigm (Chaouat, 2010(Chaouat, , 1417(Chaouat, 2016Moffett & Loke, 2004, 2006Mor et al., 2011;Stadtmauer & Wagner, 2020b;Yoshizawa 1418Yoshizawa 2016. Moffett & Loke (2006) caution against conceptualizing embryos as analogs of allografts. ...
... In mammals, immunological cells at the maternal-fetal interface may not function through 1480 self-non-self-discrimination, as they are understood to function in the rest of the body (Chaouat, 1481 as 'maternal-fetal intra-action' given the dynamics between maternal and fetal immune systems 1483 in mammals (Yoshizawa, 2016). It is unclear if these insights apply to other viviparous amniotes. ...
... (3) Growing evidence in the medical literature suggests that immune system interactions at 1880 the maternal-fetal interface in mammals did not evolve simply through tolerance, 1881 evasion, or suppression (Chaouat, 2016;Moffett & 1882Loke, 2004, 2006. Instead, maternal-fetal immune dynamics have a deep evolutionary 1883 history that enables both embryo and mother interact cooperatively (Yoshizawa, 2016). 1884 ...
Across amniotes, squamates represent the only clade with highly variable parity modes, oviparity (egg-laying) and viviparity (live-birth). Despite this, relatively little is known about how oviparity and viviparity evolve at the genomic and physiological levels in squamates. Within the context of interdisciplinary medical, poultry science, and reproductive biology literature, I review the genomics and physiology of reproduction across five broad processes expected to change during transitions between parity modes—eggshell formation, embryonic retention, placentation, calcium transport, and maternal-fetal immune dynamics. This review is the first time that the maternal-fetal immune dynamics of squamates is considered in the context of modern medical literature, where embryos are no longer conceptualized as analogs to allografts. I offer alternative perspectives and holistic hypotheses on the genomic and transcriptomic drivers of parity mode transitions in squamates. Two new pathways through which early Lepidosaurs may have transitioned rapidly between oviparity and viviparity with no intermediate stages are presented. Overall, the physiology of reproduction illuminates the biological plausibility of highly labile parity modes in some squamate lineages, with constrained parity modes in others. Future research should be open to either possibility unless clade-specific biological evidence suggests otherwise. Rather than emphasizing the feasibility of transitions in either direction, I posit that oviparity and viviparity are relatively minor variations of a shared process.
... For example, Blackman and Venn (2010: 7) describe how shared ontologies across biology, social sciences and the humanities now 'emphasize the fact that social and natural phenomena are complex, processual, indeterminate, relational and constantly open to effects from contiguous processes' (Blackman, 2016). Others note how such 'new biologies' (Meloni et al., 2016) are distinctively 'intra-actional' (Yoshizawa, 2016), 'exposed' (Murphy, 2008), 'situated' (Niewöhner and Lock, 2018), 'entangled with' (Barad, 2003), 'embedded in' (Lock, 2015;Niewöhner, 2011) and 'constituted by' (Landecker, 2016) the historical present (Baedke, 2017;Meloni, 2018;Warin et al., 2016). While these analyses focus on antibiotic resistance, immunology, toxicology and the microbiome, here we are specifically interested in epigenetic research on the human placenta. ...
... As a result, DOHaD research can reinforce the individualization of risk and women's responsibilities for children's health. Yoshizawa (2016) and others (Fannin, 2014;Maher, 2002) argue that current placenta research has the potential to reshape such individualistic narratives as it 'enables us to recognize, account for, and attend to diffuse responsibilities for fetal-maternal outcomes that extend beyond mothers to the biosocial milieus of pregnancy' (p. 83). ...
This article builds on feminist scholarship on new biologies and the body to describe the temporal politics of epigenetic research related to the human placenta. Drawing on interviews with scientists and observations at conferences and in laboratories, we argue that epigenetic research simultaneously positions placenta tissue as a way back into maternal and fetal bodies following birth, as a lens onto children’s future well-being, and as a bankable resource for ongoing research. Our findings reflect how developmental models of health have helped recast the placenta as an agential organ that is uniquely responsive to environments during pregnancy and capable of embodying biological evidence about the effects of in utero experiences after birth. We develop the concept of ‘recursive embodiment’ to describe how placenta epigenetics is reimagining relationships between bodies and environments across developmental, epigenetic, and generational time, and the impacts this has for experiences of pregnancy and responsibilities related to children’s health.
... Therefore, the relationship between the mother and the fetus becomes a potentially complex and risky relationship throughout the reproductive process. Hence in recent years, feminist research focused on the placenta is taking a different approach to examining the physical link and the symbolism of the pregnant woman-fetus relationship [32][33][34][35]. ...
... Although some mothers have some doubts about the transmission of PTSs and the risks that this involves, most think that there is a process of connection and differentiation in the relationship between the mother and fetus. This scientific process, known as "placentation" [33] and the "placental economy" [32,34,35], places the biological contribution of the placenta at the center of the debate, and situates it as a relational organ through which functions and materials circulate between the mother and the fetus. The maternal-fetal exchange through the placenta becomes a central issue in immunological science [34], but also in regard to internal pollution from PTSs [44,45]. ...
In this article, we analyze how pregnant and breastfeeding women perceive the inside of their bodies as well as their thoughts regarding the accumulation and elimination of chemical compounds present in food, and how these are then transmitted to the fetus. We explore different social perceptions of risk regarding the circulation of chemical compounds inside the body using qualitative research based on the technique of body mapping, comprised of women's drawings of their bodies in combination with comments on the drawings, food diaries and narratives from in-depth interviews. We examine how these 41 women (21 pregnant and 20 breastfeeding) perceive the body's internal mechanisms during the stages of pregnancy and breastfeeding, as well as the circulation of chemical contaminants within it. The body mapping technique allowed us to analyze participants' knowledge of internal pollution, a little-understood process in society. Thanks to these pregnant and breastfeeding women, who made an effort to represent and reflect on these new risks, this study shows that scientists and obstetricians need to collaborate with women in order to better understand and publicize the risks of internal pollution.
... There are modes of living physiologies that refuse to lend physiology or the Euro-Western ontologies it compels a single breath Stengers 2011): Métis scholar Zoe Todd (2014) examines human-fish relationships to detail how fish can be engaged within expansive relational frameworks lived by Indigenous Peoples in Arctic Canada; Banu Subramaniam (2014) writes with flowers, tracing how her practices of plant physiology intertwine with different disciplines and gendered dynamics across India and America; vaginas are a site of Kanien'keha:ka refusal with Emily Coon (2020), who thinks flesh beyond colonial gendered narratives of reproduction; and Kim TallBear (2013) theorizes genomic knowledges with Indigenous sciences and relationalities. From the biosciences come a multitude of feminist methodologies of doing science otherwise: tracing metabolisms (Landecker 2011(Landecker , 2013; heart feminism (Pollock 2015); thinking fetal development as transdisciplinary relationality (Yoshizawa 2016); and imagining epigenetics as obesity entanglements (Warin et al. 2015). Physiologists craft publications that contradict what the field once took to be true, troubling the underpinnings of the field they have pledged to sustain. ...
Thinking with a Canadian physical activity pedagogical resource, this article proposes that post-developmental early childhood education pedagogies can engage with physiological sciences beyond the instructive or instrumental relationships currently facilitated by contemporary physical activity pedagogies. To begin, I bring feminist science studies together with post-developmental pedagogies to detail how pedagogy and physiology become intertwined. I trace the tensions of weaving physiological knowledges with pedagogies, acknowledging the power-laden complexities of thinking with Euro-Western sciences in Canadian education. Finally, I work through two propositions aimed at making physiological knowledges differently entangled with the complexities of post-developmental pedagogies: (1) crafting physiological knowledges as a problem with pedagogies, while (2) deploying these physiological knowledges as pedagogical provocations that call us to engage differently with physiological knowledges.
... Az adatok szerint a prolongált terhesség kifejlődésének ez az ellentmondásos (kialakul, de valójában gátolt kellene, hogy legyen) folyamata különbözik a Medawar által 1953-ban előterjesztett és jól ismert "immunológiai paradoxon"-tól (az immunológiai kilökődés kérdése), de egyúttal ki is egészíti azt [22]. Arra is rámutattak, hogy a conceptus immunológiaiparadoxon-elmélete, amely a magzat szemiallogén statusára utal, idáig kissé félrevezette a kutatást és a klinikai gyakorlatot [23][24][25]. ...
The aim of this review is to explore, in addition to revealing the biological background, new conceptual and therapeutic approaches for reproductive clinicians to provide better and more effective care for sterile and infertile couples. In humans, 75% of unsuccessful pregnancies are the result of failures of implantation, and implantation failure is the limiting factor for in vitro fertilization treatment. A modified “good” inflammation is necessary for implantation and parturition, but for most of pregnancy, inflammation threatens the continuation of pregnancy. During this period, maintaining the non-inflammatory condition is extremely important, enabling the maternal epigenetic effects to occur in the fetus, making it possible for the offspring to adapt as much as possible to the extrauterine life. In the maintenance of the non-inflammatory condition of pregnancy, a large amount of progesterone hormone produced by the placenta (after the luteo-placental shift) plays a crucial role. It has been reported that the role of inflammation during implantation is an ancestral response to the embryo as a foreign body. During normal pregnancy, this inflammation is initiated by the trophoblast and involves the suppression of neutrophil infiltration, the recruitment of natural killer cells to the site of implantation as well as the production of a range of proinflammatory cytokines. During the “implantation window”, the uterus is primed to produce several inflammatory signals such as prostaglandin E 2 and a range of proinflammatory cytokines, including TNF, IL6 and IFNγ. The feto-placental unit is a semi-foreign graft called a “semi allograft”, and the recognition of pregnancy by the mother (host) and the resulting maternal immune tolerance is an essential part of successful pregnancy and the birth of a healthy fetus. Because of the functional or absolute reduction of circulating progesterone (due to the decreasing hormone production of the physiologically “aging” placenta after around the 36th week of pregnancy) progesterone effects become insufficient. Therefore it is unable to suppress the production of IL8 and other inflammatory cytokines and the term inflammation, leading to cervical ripening, uterus contractions and parturition (“good” inflammation). Orv Hetil. 2019; 160(32): 1247–1259.
... Placenta science research commonly accepts a definition of the placenta 3 based on two assumptions: (1) that placentas are intra-uterine tissues that perform a function during pregnancy alone; and (2) that maternal and fetal needs for the placenta are temporary. As such, these assumptions differentiate non-'natural' meanings of placentas as beyond the interest of science (see Yoshizawa, 2016). This determination effectively precludes a recognition that different and/or postpartum purposes necessitated by women, infants, or communities might be important for understanding the placenta in science and medicine. ...
An estimated 50 million kilograms of human placental material is produced worldwide every year. In countries such as Canada, human placentas are utilized in scientific research concerned with fetal and women’s health, immunology, and cancer, to name a few. Through an empirical study involving interviews with placenta scientists and observations of placental science research laboratories and meetings, this article examines the material and discursive processes through which placentas are rendered materially and ethically available for scientific study. We argue that these processes involve a critical shift in placenta ontology such that placentas exist as waste and not-waste, an indeterminacy that is resolved in a four-phase praxis. The praxis ultimately makes placentas not only available, but also monetarily and morally ‘free of charge’ for scientific purposes. Our analysis reveals that the purported waste-ness of placentas potentiates their amenability to scientific experimentation, and is foundational to scientists’ claims about their moral relationship with broader publics.
... We will argue that this obstacle for the evolution of an extended pregnancy is different from and in addition to the well-recognized 'immunological paradox' proposed by Medawar in 1953 [10]. It has even been argued that the concept of the immunological paradox, which conceptualizes the fetus as a semi-allograft, has been misleading both for research and for clinical practice [11][12][13]. ...
A widely discussed physiological puzzle of mammalian pregnancy is the immunological paradox, which asks: why is the semi-allogenic fetus not attacked by the mother's adaptive immune system? Here, we argue that an additional, and perhaps more fundamental paradox is the question: why is embryo implantation so similar to inflammation while inflammation is also the greatest threat to the continuation of pregnancy? Equally puzzling is the question of how this arose during evolution. We call this the inflammation paradox. We argue that acute endometrial inflammation was ancestrally a natural maternal reaction to the attaching blastocyst, a situation still observed in the opossum. Eutherian implantation arose through a transformation of the acute inflammation into a process essential for implantation by causing vascular permeability and matrix reorganization as well as by suppressing the effects deleterious to the fetus. We propose that this model allows us to understand the differences between 'good inflammation' and 'bad inflammation'. Further, it allows us to understand the influence of inflammation on the outcome of pregnancy and maternal health.
In cultures where reproduction is highly medicalised, pregnancy is often understood in terms of foetal development and an anticipated baby. This is connected to a wider privileging of the ‘foetal subject’ in these settings, which has had implications for reproductive autonomy. In this article, I disrupt dominant understandings of pregnancy by engaging with qualitative accounts of gestational trophoblastic disease. This rare condition can entail experiences of pregnancy without foetal development, allowing for scholarly attention to the wider biological, affective and relational constituents of this corporeal event. In this article, I pay particular attention to the ‘pregnancy hormone’ human chorionic gonadotropin (hCG), which in the context of gestational trophoblastic disease becomes a biomarker for disease. My research extends feminist science studies perspectives destabilising understandings of maternal and foetal bodies as bounded and distinct entities. The article de-centres foetal development as the most significant consequence of conception and enriches feminist discussions of reproductive politics.
There is a current lack of consensus on whether the ancestral parity mode was oviparity (egg‐laying) or viviparity (live‐birth) in amniotes and particularly in squamates (snakes, lizards, and amphisbaenids). How transitions between parity modes occur at the genomic level has primary importance for how science conceptualises the origin of amniotes, and highly variable parity modes in Squamata. Synthesising literature from medicine, poultry science, reproductive biology, and evolutionary biology, I review the genomics and physiology of five broad processes (here termed the ‘Main Five’) expected to change during transitions between parity modes: eggshell formation, embryonic retention, placentation, calcium transport, and maternal–fetal immune dynamics. Throughout, I offer alternative perspectives and testable hypotheses regarding proximate causes of parity mode evolution in amniotes and squamates. If viviparity did evolve early in the history of lepidosaurs, I offer the nucleation site hypothesis as a proximate explanation. The framework of this hypothesis can be extended to amniotes to infer their ancestral state. I also provide a mechanism and hypothesis on how squamates may transition from viviparity to oviparity and make predictions about the directionality of transitions in three species. After considering evidence for differing perspectives on amniote origins, I offer a framework that unifies ( i ) the extended embryonic retention model and ( ii ) the traditional model which describes the amniote egg as an adaptation to the terrestrial environment. Additionally, this review contextualises the origin of amniotes and parity mode evolution within Medawar's paradigm. Medawar posited that pregnancy could be supported by immunosuppression, inertness, evasion, or immunological barriers. I demonstrate that this does not support gestation or gravidity across most amniotes but may be an adequate paradigm to explain how the first amniote tolerated internal fertilization and delayed egg deposition. In this context, the eggshell can be thought of as an immunological barrier. If serving as a barrier underpins the origin of the amniote eggshell, there should be evidence that oviparous gravidity can be met with a lack of immunological responses in utero . Rare examples of two species that differentially express very few genes during gravidity, suggestive of an absent immunological reaction to oviparous gravidity, are two skinks Lampropholis guichenoti and Lerista bougainvillii . These species may serve as good models for the original amniote egg. Overall, this review grounds itself in the historical literature while offering a modern perspective on the origin of amniotes. I encourage the scientific community to utilise this review as a resource in evolutionary and comparative genomics studies, embrace the complexity of the system, and thoughtfully consider the frameworks proposed.
O presente texto, apresenta dois momentos da filosofia de Luce Irigaray: a crítica à ontologia do matricídio e a proposta de uma ontologia atenta ao processo de placentação. Para isso dois textos são evocados: Le Corps à Corps avec la mère e À propos de l’ordre maternel. O texto acompanha as reflexões propostas pela autora belga, apontando que a atenção ao processo material de placentação pode dar origem a uma ontologia relacional que sirva de contraponto a um individualismo metafísico. Para apresentar os termos dessa oposição, o texto reflete sobre a panóptica do útero exemplificada pela imagem Spaceman de Lennart Nilsson: ao retratar o feto como um astronauta, Nilsson produz o apagamento da gestante. A figura está investida no processo de humanização do feto, e pela efetuação do matricídio como apagamento. A atenção para o processo de placentação, por outro lado, permite entender o processo coletivo de vir-a-ser. Na tensão (política) entre as duas ontologias, individualismo e relacionalidade estão em jogo e, por isso mesmo, estão também em jogo distintas formas de habitar o mundo.
In this Introduction, we present a collection of articles under the topic “the reproductive bodies of postgenomics.” Through individual and collective research, the articles explore—sociologically, ethnographically, and philosophically—how bioscience in the postgenomic age is changing our understanding of reproductive bodies, and more broadly, how it is challenging existing ideas of heredity, embodiment, kinship, and identity. Feminist and postcolonial theories of technoscience are at the heart of this collection, and our aim is to further biosocial thinking while being cognizant that practices of postgenomics also continue to reproduce deterministic paradigms. The concepts of “knowledge,” “experience,” and “justice” form the reference points animating our investigations. We bring these concepts into conversation with one another to disentangle how postgenomics operate differently on the reproductive body, namely on the levels of practice, discourse, and norms. This is an important exercise as it will enable social science and humanities scholars to evaluate the political capacities of postgenomics for the future study of reproduction.
In gestational surrogacy arrangements, the womb is often figured as a holding environment that brings the child of commissioning parents to fruition but does not shape fetal identity. This article probes the racial imaginary of such a figuration—what I term the “nonracializing womb”—where gestation is seen as peripheral to racial transmission. Drawing on feminist science studies frameworks and data from interviews with parents who commissioned surrogates, this article traces the cultural politics of the nonracializing womb, positioning it as an index for broader understandings of race, reproductive labor, and kinship that hinge on nuclear and biogenetic forms. It then problematizes this figure of gestation by engaging emerging research on environmental epigenetics, which offers a lively model of pregnancy as shaping fetal biology, blurring the lines between surrogate and fetus. I argue that epigenetics offers a resource to reimagine gestation as a racializing process, by theorizing race not as solely genetic, but as relational, socio-environmental, and forged through distributed kinship lineages.
This article, part of a historical study of childbirth in the Sahel, draws upon oral interviews, ethnographic materials, and studies of midwifery to explore placenta burial in Niger. In the region the placenta is often referred to as the “traveling companion” that ushers the new human from one world to the next. Only through proper respect toward the placenta by means of careful burial can a woman’s future fertility be protected. The importance of protecting a woman’s future reproductive capacity accounts for both the centrality of this ritual to childbirth and for the appeal of the ritual expertise of elderly “traditional birth attendants” despite access to bio-medically trained midwives. Protecting a vulnerable parturient mother from the envy of those (such as co-wives) who might “tie up” her womb is an integral part of the process of childbirth. Appropriate placenta burial orchestrated by a woman’s therapy management group makes good on the cyclical intergenerational entrustment through which ancestors and descendants endure in a cycle linking birth and death, planting, and burial. “Traditional” rituals bear marks of major shifts in the agricultural economy, rapid urbanization, and ongoing adoption and reinterpretation of Islam. Multi-generational interviews reveal that across a broad range of ethnicities, status groups, and educational profiles, women in Niger share a concern for proper placenta burial. This approach to preserving women’s reproductive health and fertility is shared by adjacent neighbors, generations, and ethnicities.
During the twentieth century, genes were considered the controlling force of life processes, and the transfer of DNA the definitive explanation for biological heredity. Such views shaped the politics of human heredity: in the eugenic era, controlling heredity meant intervening in the distribution of "good" and "bad" genes. However, since the turn of the twenty-first century, this centrality of genes has been challenged by a number of "postgenomic" disciplines. The rise of epigenetics in particular signals a shift from notions of biological fixedness to ideas of plasticity and "impressionability" of biological material.
This book investigates a long history of the beliefs about the plasticity of human biology, starting with ancient medicine, and analyses the biopolitical techniques required to govern such permeability. It looks at the emergence of the modern body of biomedicine as a necessary displacement or possibly reconfiguration of earlier plastic views. Finally, it analyses the returning of plasticity to contemporary postgenomic views and argues that postgenomic plasticity is neither a modernistic plasticity of instrumental management of the body nor a postmodernist celebration of potentialities. It is instead a plasticity that disrupts clear boundaries between openness and determination, individual and community, with important implications for notions of risk, responsibility and intervention.
The placenta has played an important role in feminist theories of subjectivity; however, the placenta of feminist theory has been the fully functional placenta of what is considered a successful full-term pregnancy. Pregnancy loss, a topic that has been generally overlooked within feminist scholarship, is absent from feminist theories of the placenta. This article uses early placental development, particularly development that takes place before the placenta becomes fully functional as an organ for hormone production and interchange, as a space through which to consider theorising subjectivity, reproduction and relation through pregnancy loss. In so doing, I argue that turning our attention to the placenta’s early development, regardless of outcomes, allows us to reimagine the role of process for feminist theories of subjectivity while also making room for a wider array of pregnancy outcomes, reinvigorating our ability to think about relations and models of hospitality that do not end as we might imagine.
A large body of literature engages with personal accounts of pregnancy to illustrate the subjugation of women's embodied experience by practices of biomedicine. This article explores this issue through women's accounts of sensing initial foetal movement, drawn from qualitative interviews with 15 women resident in the UK. Participants depict this aspect of pregnant embodiment as ambiguous and indefinite, in contrast to clinical and popular representations of foetal movement. In highlighting the uncertainties characteristic of this corporeal event, the article adds to literature destabilising understandings of pregnant women's and foetal bodies as bounded and distinct. Ambiguous experiences of foetal movement arise in the context of sociocultural framings of pregnancy as ‘at risk’, and in turn, may be seen to contribute to these representations, with some participants articulating that uncertain sensations could provoke anxiety. In this article, perceptions of foetal movement are emphasised as valuable to women, and as inextricable from the social settings in which they emerge. This research has implications for sociological and feminist discussions of pregnancy, and work exploring the mutual shaping of corporeality and sociocultural contexts more widely.
Breast milk and the placenta are phenomena of female human embodiment that challenge the philosophical notion of separate, sovereign subjects independent of other human beings and an objective world "out there." A feminist phenomenological analysis, indebted to Merleau-Ponty and Irigaray, reveals placenta and milk to be intercorporeal, "chiasmic" forms of shared organic existence. This analysis is a philosophical and psychological exploration of "matrotopy," i.e., the fact that humans eat their mothers through breast milk and placenta. This exploration, however, requires an understanding of the larger environmental field which sustains the female body and its offspring. Environmental degradation, particularly through estrogen mimicking substances in plastics and pesticides, targets the endocrine system of developing fetuses and endangers the future of the human speciesyrom the inside. Invisible organo-chemical technologies pose a new and immediate danger and ethical challenge to women and men in the twenty-first century. A "placental ethics" respects the insertion of the human being into the dynamic field of nature; it calls for an awareness that, unless we develop a changed attitude toward technology, the gradual extinction of our species continues to happen in female bodies today.
The placenta is arguably the most important organ of the body, but paradoxically the most poorly understood. During its transient existence, it performs actions that are later taken on by diverse separate organs, including the lungs, liver, gut, kidneys and endocrine glands. Its principal function is to supply the fetus, and in particular, the fetal brain, with oxygen and nutrients. The placenta is structurally adapted to achieve this, possessing a large surface area for exchange and a thin interhaemal membrane separating the maternal and fetal circulations. In addition, it adopts other strategies that are key to facilitating transfer, including remodelling of the maternal uterine arteries that supply the placenta to ensure optimal perfusion. Furthermore, placental hormones have profound effects on maternal metabolism, initially building up her energy reserves and then releasing these to support fetal growth in later pregnancy and lactation post-natally. Bipedalism has posed unique haemodynamic challenges to the placental circulation, as pressure applied to the vena cava by the pregnant uterus may compromise venous return to the heart. These challenges, along with the immune interactions involved in maternal arterial remodelling, may explain complications of pregnancy that are almost unique to the human, including pre-eclampsia. Such complications may represent a trade-off against the provision for a large fetal brain.
© 2015 The Author(s) Published by the Royal Society. All rights reserved.
Feminist analyses have made important contributions to the sociocultural experiences of pregnancy, birth and breastfeeding. This article draws upon recent theorizing within science studies to focus on the mattering of these processes. Specifically, the article expands upon Mauss's notion of the ‘gift’, which Diprose develops through the idea of ‘corporeal generosity’. I am interested in corporeal generosity insofar as it circumvents descriptions of relationships in terms of a closed economy in which resources are exchanged without excess or remainder. Corporeal generosity refers to the often missed but nevertheless inescapable debt that a body owes to other bodies. At the same time, this embodied ‘gifting’ is both unpredictable and intrusive – there is as much possibility of threatening the integrity of bodies as there is of opening new possibilities.
In this article I describe the main imagery currently used in popular and scientific descriptions of the immune system in the United States: the body as nation state at war over its external borders, containing internal surveillance systems to monitor foreign intruders. Although in some respects this is a boundary-oriented, internally flat system, in other respects it contains suppressed hierarchies that draw on cultural concepts of race and gender. I suggest what kinds of ideological work such imagery may be doing and what uses people make of it. Other models of the body and immune responses that build on different imagery are described.
The existence of allogeneic cells within an individual has been demonstrated in multiple fields such as hematopoietic stem cell or solid organ transplantation, non-depleted blood transfusions and the most common form which is bidirectional maternal-fetal cell trafficking, whereby cells from the fetus pass through the placental barrier. In order to graphically illustrate this early natural phenomenon that initiates the journey of a child's cells within the mother's blood and other tissues, we used a new procedure in microscopy imaging generating Large Scale Panoramic Pictures (LSPP). This technique can also be extended to explore a broad diversity of experimental models.
Stability and function of eukaryotic genomes are closely linked to chromatin structure and organization. During cell division the entire genome must be accurately replicated and the chromatin landscape reproduced on new DNA. Chromatin and nuclear structure influence where and when DNA replication initiates, whereas the replication process itself disrupts chromatin and challenges established patterns of genome regulation. Specialized replication-coupled mechanisms assemble new DNA into chromatin, but epigenome maintenance is a continuous process taking place throughout the cell cycle. If DNA synthesis is perturbed, cells can suffer loss of both genome and epigenome integrity with severe consequences for the organism.
Low birthweight is now known to be associated with increased rates of coronary heart disease and the related disorders stroke, hypertension and non-insulin dependent diabetes. These associations have been extensively replicated in studies in different countries and are not the result of confounding variables. They extend across the normal range of birthweight and depend on lower birthweights in relation to the duration of gestation rather than the effects of premature birth. The associations are thought to be consequences of developmental plasticity, the phenomenon by which one genotype can give rise to a range of different physiological or morphological states in response to different environmental conditions during development. Recent observations have shown that impaired growth in infancy and rapid childhood weight gain exacerbate the effects of impaired prenatal growth. A new vision of optimal early human development is emerging which takes account of both short and long-term outcomes.
OverviewThe placenta at delivery: Starting at the end to understand the beginningBack to the beginning with decidualizationPlacental development from implantation through the first trimesterA villous tree developsTypes of villiComponents of the villous coreMultiple phenotypes of trophoblast evolve from the trophectodermPlacental fibrinoidConclusion
References
Science produces fascinating puzzles: why is there such a range of placental structures when other mammalian organs are so structurally uniform ? Why and how did the different placental structures evolve ? Comparative placental studies can facilitate the identification of the common factors in placental growth, differentiation and function and their relevance to possible evolutionary pathways. Comparative Placentation is the only book presenting up-to-date data illustrating the great variety of structure but uniform function of vertebrate placentas from fish to man. This information is essential for selection of suitable models to investigate particular practical problems of impaired or anomalous growth in human and animal placentation. The unique collection of the best light and electron micrographs from the last thirtyfive years which precisely illustrate the structural range in each taxon, make the book the most authoritative publication in this field and a vital source of information for anyone interested on reproductive physiology, anatomy and medicine.
Discarded at birth, the placenta is a highly complex and fascinating organ. During the course of a pregnancy, it acts as the lungs, gut, kidneys, and liver of the fetus. The placenta also has major endocrine actions that modulate maternal physiology and metabolism and provides a safe and protective milieu in which the fetus can develop. The human placenta undergoes dramatic transformations in form and function between the first trimester, when organogenesis occurs, and the remainder of pregnancy that reflect evolutionary responses to changing oxygen concentrations in the earth's atmosphere. Recent research indicates a more interactive dialogue between the placenta and the maternal tissues than previously recognized. The endometrial glands provide histotrophic support during the first weeks of pregnancy, and the placenta appears able to stimulate its own development by up-regulating gland activity in response to endocrine signals. Extravillous trophoblast cells migrate from the placenta into the uterine wall, in which they interact with cells of the maternal innate immune system. These interactions have a physiological, rather than a classical immunological, outcome and most probably mediate remodeling of the uterine spiral arteries that supply the placenta. Furthermore, deportation of aggregates of transcriptionally active trophoblast nuclei, and the release of exosomes carrying microribonucleic acids challenge our perceptions of fetal-maternal signaling and where the placental interface actually lies. Here we reconsider definitions of the placenta in the light of these recent advances.
Maternal recognition of pregnancy reflects the various ways in which the mother responds to the presence of a conceptus within her reproductive tract. A part of the biochemical information she senses may be irrelevant to pregnancy outcome, but some reflects the attempts by the conceptus to gain some measure of control over corpus luteum function, uterine blood supply, the mother's immune system, and other aspects of maternal physiology. Most probably as a result of ongoing genetic conflict between the mother and the conceptus, a bewildering range of placental structures and trophoblast signaling mechanisms are encountered in eutherian mammals despite the fact that the uterus and conceptus share a common interest, which is the successful outcome of the pregnancy. Here we review some of the ways that such mammals maintain luteal function in early pregnancy and briefly discuss the related topics of embryonic loss and maternal monitoring of conceptus fitness. We next address the view that the conceptus is an intruder, recognized as foreign by the mother, that likely survives by using strategies analogous to those employed by successful parasites. In this context, we describe the pregnancy-associated glycoproteins, multiple isoforms of which are released at the trophoblast-endometrial interface during pregnancy of ungulate species. These molecules, which are structurally related to pepsin, are proposed to bind and sequester antigenic peptides, thereby serving an immunoprotective role.
IntroductionImportance of maternal nutrients for fetal developmentFactors affecting placental capacity for nutrient transferPlacental nutrient synthesis and metabolismPlacental hormone synthesis and metabolismMechanisms of placental programmingSummaryReferences
This essay explores the act of touching as it takes place in physical matter, in theorizing, and in the productive spaces where the two are indistinguishable. First, the author considers how feminist theory goes about touching science and unpacks touch as an act that reveals the self within the other and the other within the self. The essay then offers a tutorial in quantum field theory to prepare the reader for an unexpected interlocutor on the topic of touching: the electron. As Barad demonstrates with descriptions of electrons and how they have troubled physicists to the point of being “normalized” and called “immoral,” these particles resist normative notions of physical contact; they are perverse. On the human scale, electrons trouble the notion of touch by making it impossible to close the distance between atoms: the sense of touch paradoxically relies on electric repulsion between neighboring objects. On the subatomic scale, each electron gleans its energy from touching itself as if undergoing an exchange with another. Not only does the presence of contact come from its absence but also the presence of electrons themselves relies on a void holding their virtual counterparts. On every level, one can never reach the other—even the other within oneself. This paradox on the micro scale that constitutes all macro-scale matter calls into question the spatial and temporal fixity of identity. Barad shows that the notion of a unified, autonomous self is problematic not just on the personal level but on the particle level as well, and she responds to this deconstruction of matter with an ethics of response-ability.
Within geographical research on 'the body', a focus on the surfaces of bodies has been useful for considering how body boundaries, most often implied to begin and end at the skin, (de)limit, (de)regulate, and (de)stabilise what we come to know as 'a body'. Such work draws attention to how meaning is inscribed 'upon' such surfaces and on the fluids that move across, within, and through those surfaces: for example blood, breast milk, and excrement. This paper, however, considers the potential for thinking geographically about interior bodily surfaces by engaging with the placenta. The placenta is a temporary organ that forms in a woman's body only during pregnancy and whose purpose is to mediate the flow of substances between a woman's body and the foetus. It is often considered to have two surfaces, the maternal and foetal surface, or to be 'a' surface in and of itself. Our intention is to think geographically 'with' the placenta' in order to focus on what interior surfaces can 'do' rather than 'what they mean'. In so doing our contribution is twofold. Firstly, we will focus on the 'resurfacing' of the placenta when it moves outside of the body to be placed upon other (bodily) surfaces, taken back inside the body of origin, or put to use in research. This is significant for highlighting the specific mobilities and temporalities of interior bodily surfaces. Secondly, we consider the theoretical and ethical significance of the placenta for geography by engaging with Luce Irigaray's account of the placental relation between mother and foetus understood as a space of mediation or 'space between two'. In particular we are interested in considering the geographical potential of the sexed specificities of interior body surfaces, or their 'morpho-logics', for understandings of relationality, between self and other, and body and world; in short, we work with the placenta as a 'relational organ' in order to uncover new and potentially enlivening ethical spaces of exchange.
How much of philosophical, scientific, and political thought is caught up with the idea of continuity? What if it were otherwise? This paper experiments with the disruption of continuity. The reader is invited to participate in a performance of spacetime (re)configurings that are more akin to how electrons experience the world than any journey narrated though rhetorical forms that presume actors move along trajectories across a stage of spacetime (often called history). The electron is here invoked as our host, an interesting body to inhabit (not in order to inspire contemplation of flat-footed analogies between ‘macro’ and ‘micro’ worlds, concepts that already presume a given spatial scale), but a way of thinking with and through dis/continuity – a dis/orienting experience of the dis/jointedness of time and space, entanglements of here and there, now and then, that is, a ghostly sense of dis/continuity, a quantum dis/continuity. There is no overarching sense of temporality, of continuity, in place. Each scene diffracts various temporalities within and across the field of spacetimemattering. Scenes never rest, but are reconfigured within, dispersed across, and threaded through one another. The hope is that what comes across in this dis/jointed movement is a felt sense of différance, of intra-activity, of agential separability – differentiatings that cut together/apart – that is the hauntological nature of quantum entanglements.
Breast milk and the placenta are phenomena of female human embodiment that challenge the philosophical notion of separate, sovereign subjects independent of other human beings and an objective world “out there.” A feminist phenomenological analysis, indebted to Merleau-Ponty and Irigaray, reveals placenta and milk to be intercorporeal, “chiasmic” forms of shared organic existence. This analysis is a philosophical and psychological exploration of “matrotopy,” i.e., the fact that humans eat their mothers through breast milk and placenta. This exploration, however, requires an understanding of the larger environmental field which sustains the female body and its offspring. Environmental degradation, particularly through estrogen mimicking substances in plastics and pesticides, targets the endocrine system of developing fetuses and endangers the future of the human species from the inside. Invisible organo-chemical technologies pose a new and immediate danger and ethical challenge to women and men in the twenty-first century. A “placental ethics” respects the insertion of the human being into the dynamic field of nature; it calls for an awareness that, unless we develop a changed attitude toward technology, the gradual extinction of our species continues to happen in female bodies today.
Obesity is the object of incredible amounts of resources and attention purportedly aimed at reducing corpulence and increasing health. Despite this, consensus with respect to the definition, causes or solutions is lacking, making obesity a prominent knowledge controversy. In this article, I argue that the Barker hypothesis, a theory of foetal development, can support the redistribution of expertise necessary to address this knowledge controversy. A vast scientific literature confirms its argument that many diseases can be traced to the conditions for development in utero determined by the commingling of temporally and spatially complex processes. The Barker hypothesis does not support solely reductionist, biophysiological paradigms of health and disease, but rather evinces complex understandings that span biology, social positionality, place and generation. I argue that this makes the hypothesis significant for transdisciplinary studies of health and disease, and prompts consideration beyond the conventional bounds of epidemiology to new sites of understanding and action that may support movements concerned with body politics and justice for fat people. I point to literature on the potential for injustice engendered by the Barker hypothesis, and suggest that these critiques reveal the very necessity for transdisciplinary collaboration on obesity in the first place.
More and more areas of medicine involve subjects donating tissues to another — blood, organs, bone marrow, sperm, ova and embryos can all be transferred from one person to another. Within the technical frameworks of biomedicine, such fragments are generally treated as detachable things, severed from social identity once they are removed from a particular body. However an abundant anthropological and sociological literature has found that, for donors and patients, human tissues are not impersonal. They retain some of the values of personhood and identity, and their incorporation often has complex effects on embodied identity. This article draws on feminist philosophy of the body to think through the implications of some of these practices. Specifically, it draws on the idea of intercorporeality, wherein the body image is always the effect of embodied social relations. While this approach is highly productive for considering the stakes involved in tissue transfer, it is argued that the concept of body image has been too preoccupied with the register of the visual at the expense of introceptive data and health/illness events. Empirical data around organ transplant and sperm donation are used to demonstrate that the transfer of biological fragments involves a profound kind of intercorporeality, producing identifications and disidentifications between donors and recipients that play out simultaneously at the immunological, psychic and social levels.
This article is a phenomenological exploration and description of certain selected aspects of living the specificities and conundrums posed by what is usually, if problematically, called a ‘phantom limb’. Using my own body as an ‘intimate laboratory’, I attend to the dynamics and mutability of the supposed ‘phantom’, both during the post-operative period of the above-the-knee amputation of my left leg as well as after I began to use and incorporate my prosthetic leg. Throughout, I explore the reversible aspects of my two legs as ‘phantom’ and ‘real’, present and absent, and visible and invisible — paying attention, as well, to the lived and linguistic sense we make of our bodies in ‘parts’ and our bodies as ‘whole’.
We have no interest whatever in minimizing the continuing history of racist, sexist, homophobic, or otherwise abusive biologisms, or the urgency of their exposure, that has made the gravamen of so many contemporary projects of critique. At the same time, we fear — with installation of an automatic antibiologism as the unshifting tenet of `theory' — the loss of conceptual access to an entire thought-realm. (Sedgwick and Frank, 1995: 15)
I was left wondering what danger had been averted by the exclusion of biology. What does the nominative `biological or anatomical body' actually refer to? And what secures the separation of its inadmissible matter from the proper purview of Irigaray's textual interventions? When I asked a question to this effect it was met with a certain nervous comprehension. Deciding, perhaps, that I must still be immersed in a precritical understanding of the body, the speaker dismissed me with a revealing theatrical gesture. As if to emphasize the sheer absurdity of my question she pinched herself and commented `Well I don't mean this body'. And so it seemed with a gesture so matter of fact that it required no further comment, the fact of (the) matter was both decided and dispatched. (Kirby, 1997: 70)
Feminism has been as deeply implicated in routinized antiessentialism as any of our critical procedures. Even though questions of `the body' have become increasingly fashionable in all manner of feminist projects (surely `the body' has become, in a very short space of time, one of our most routinized theoretical gestures), the schedule of feminism's antibiologism has been little altered. In most of these projects on `the body', the body in question is pursued in its socially, experientially, or psychically constituted forms, but rarely in its physiologically, biochemically, or microbiologically constituted form, the idea of biological construction having been rendered either unintelligible or naive. Despite an avowed interest in the body, there is a persistent distaste for biological detail. (Wilson, 1998: 14—15)
These feminist theories have usually been reluctant to engage with biological data: they retain, and encourage, the fierce antibiologism that marked the emergence of second wave feminism. (Wilson, 2004: 13)
That feminist scholars are particularly prone to a `knee jerk constructivism' helps explain the reluctance of those in the humanities to engage seriously with the claims of science. (Squier, 2004: 46)
This book functions primarily as a reminder to social, political, and cultural theorists, particularly those interested in feminism, antiracism and questions of the politics of globalisation, that they have forgotten a crucial dimension of research, if not necessary to, then certainly useful for more incisively formulating the concepts on which they so heavily, if implicitly rely. It is written as a remembrance of what we have forgotten — not just the body, but that which makes it possible and which limits its actions: the precarious, accidental, contingent, expedient, striving, dynamic status of life in a messy, complicated, resistant, brute world of materiality, a world regulated by the exigencies, the forces, of space and time. We have forgotten the nature, the ontology, of the body, the conditions under which bodies are encultured, psychologized, given identity, historical location, and agency. We have forgotten where we come from. (Grosz, 2004a: 2)
In a recent article, Sara Ahmed castigates so-called new materialist theorists for their accusations of a biophobia evident in feminism. Biophobia is taken simply to be the claim that feminists do not engage with biological detail in their theorizations, which is demonstrably not the case. However, an elaboration of new materialist usage of biophobia reveals that they are proposing a particular conceptualization of what an engagement with the biological means. They theorize an entanglement and non-separability of the biological with/in sociality, and what they criticize in much feminism is the conventional assumption that the biological and the social are two separate and discrete systems that then somehow interact. If the new materialist arguments are fully contextualized and then applied to the supporting examples given in the article, the new materialist critique is actually borne out.
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Medical reproductive technologies have generated two new types of patients: ‘couples’ in infertility treatment and ‘fetuses’ in prenatal medicine. Using concepts from science and technology studies, specifically Latour’s (1993) notions of hybridity, mediation and purification, this article argues that these new patients are constructed in the very process of technological intervention in women’s bodies, while at the same time their constitutive role is erased from the medico-scientific accounts of these practices. Focusing on two discursive patterns found in the scientific discourses on IVF as a treatment for male infertility, and fetal surgery for various congenital problems, the article shows how conceiving of couples and fetuses as patients allows many of the actual interventions on women to be ‘deleted’ from the accounts, while simultaneously presenting these interventions as being primarily about the treatment of men and children. The article exemplifies how a (feminist) constructivist analysis of the co-constitutive relation between technology and bodies (‘nature’) can avoid essentalism while retaining a critical perspective.
In recent years, feminist theorists have examined the use of visual technologies in pregnancy and argued that these technologies are reconstructing the meaning of pregnancy. The imaged body of gestation can be deployed to distinguish and separate maternal and foetal interests. Drawing on this work, ‘Visibly Pregnant: Toward a placental body’ argues that the use of visual technology also obfuscates that which it purports to make clear. The images produced by these technologies in particular do not locate and acknowledge the significance of the placenta as a point of connection and distinction for the gestating body. The possibilities suggested by a concentration on the placenta show how the morphology of the pregnant body itself rejects the distinction outlined in the technologically produced images of pregnancy and offers some new possibilities for thinking subjectivity.Feminist Review (2002) 72, 95–107. doi: 10.1057/palgrave.fr.9400023
This text offers an understanding of the nature of scientific, mathematical and engineering practice, and the production of scientific knowledge. The author presents an approach to the unpredictable nature of change in science, taking into account the number of factors - social, technological, conceptual and natural - that interact to affect the creation of scientific knowledge. In his view, machines, instruments, facts, theories, conceptual and mathematical structures, disciplined practices and human beings are in constantly shifting relationships with one another - "mangled" together in ways that are shaped by the contingencies of culture, time and place. Situating material as well as human agency in their larger cultural context, Pickering uses case studies to show how this picture of the open, changeable nature of science advances a greater understanding of scientific work both past and present. He examines the building of the bubble chamber in particle physics, the search for the quark, the construction of the quarternion system in mathematics and the introduction of computer-controlled machine tools in industry. He uses these examples to address the most basic elements of scientific practice - the development of experimental apparatus, the production of facts, the development of theory and the interrelation of machines and social organization.
This article presents an analysis of popular UK-based guides to pregnancy. A discursive approach is adopted to explicate the interpretative repertoires used to construct pregnancy. ‘Planning for pregnancy’ incites women to engage in self-disciplining practices relating to the (pre)pregnant body, the self and ‘transforming the environment’. The easy combination and repeated use of these practices in conjunction with a repertoire of ‘pregnancy as risk’ serves to mask diversity and to decontextualize and individualize pregnancy to render it separate from women’s other relationships, identities and knowledges, with little regard for the specific circumstances in which women become/are pregnant. Medicalized discourses position women with limited agency, while, by means of repertoires of ‘choice’ informed by ‘woman-centred’ discourses, women are construed as consumers, taking responsibility for themselves and their babies. A tension is manifest in that the responsibility and blame for ‘abnormality’ or ‘unsuccessful’ outcomes is located with individual women/parents. We argue that through both medicalized and ‘womancentred’ discourses, reproduction remains a key site for the regulation of women.
This article traces the ubiquitous geopolitical metaphors used by researchers in the field of pregnancy-related microchimerism. In this research domain, immunologists and medical geneticists locate ‘non-self’ cells in women by marking Y chromosomes in cells derived from their sons. In the course of this research trajectory, experiments have yielded a number of surprises, beginning with the very presence of these cells in women decades after pregnancy. This finding confounded the expectations predicted by classical immunology, which posits the destruction of such ‘foreign’ entities. Once they were known to be present, fetal cells were implicated in pathological and destructive activity. In a series of reorientations in which metaphor, theory and practice are entangled with matter, the characterization of these cells has shifted from invaders to insurgent foreigners to assimilated productive immigrants. The article reflects on this rich domain of material-semiotic practice to demonstrate that the case of fetomaternal cell trafficking contributes to a growing uneasiness with dominant ontologies of bodies as bounded, defended, pure collectives of homogeneous inhabitants.
Recognition among molecular biologists of variables external to the body that can bring about hereditable changes in gene expression or cellular phenotypes has reignited nature/nurture discussion. These epigenetic findings may well set off a new round of somatic reductionism because research is confined largely to the molecular level. A brief review of the late nineteenth-century formulation of the nature/nurture concept is followed by a discussion of the positions taken by Boas and Kroeber on this matter. I then illustrate how current research into Alzheimer's disease uses a reductionistic approach, despite epigenetic findings in this field that make the shortcomings of reductionism clear. In order to transcend the somatic reductionism associated with epigenetics, drawing on concepts of local biologies and embedded bodies, anthropologists can carry out research in which epigenetic findings are contextualized in the specific historical, socio/political, and environmental realities of lived experience.
The immune cells that reside at the interface between the placenta and uterus are thought to play many important roles in pregnancy. Recent work has revealed that the composition and function of these cells is locally controlled by the specialized uterine stroma (the decidua) that surrounds the implanted conceptus. Here, I discuss how key immune cell types (natural killer cells, macrophages, dendritic cells, and T cells) are either enriched or excluded from the decidua, how their function is regulated within the decidua, and how they variously contribute to pregnancy success or failure. The discussion emphasizes the relationship between human and mouse studies. Deeper understanding of the immunology of the maternal-fetal interface promises to yield significant insight into the pathogenesis of many human pregnancy complications, including preeclampsia, intrauterine growth restriction, spontaneous abortion, preterm birth, and congenital infection. Expected final online publication date for the Annual Review of Immunology Volume 31 is March 19, 2013. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
Historically, several in vitro/ex vivo microscopy imaging techniques have been used to study cellular interactions within the uterus and the placenta. As these experimental methods have revealed compelling facts about the biologic phenomena of cell-cell contacts in these organs, they cannot be used to study complex dynamic behavior of living cells inside their physiologic environment. For this, recent advances in intravital imaging techniques, together with two-photon microscopy, offer an exciting opportunity to study such dynamic immunologic processes at the cellular level in the complex uterine and placental tissues. In this article, we review experimental imaging techniques that have been used for studying the uterus and placenta. In particular, we describe the advantages of intravital techniques and discuss novel procedures that can be used in reproductive immunology. We also describe several technical details involved in image sequence post-processing required to extract useful data. Finally, we conclude by discussing how the reproductive immunology field may benefit from the broad use of these intravital techniques.
Despite the development of a vast body of literature pertaining to feminism and science, examples of how feminist phifosophies might be applied to scientific theories and practice have been limited. Moreover, most scientists remain unfamiliar with how feminism pertains to their work. Using the example of the immune system, this paper applies three feminist epistemologies feminist empiricism, feminist standpoint theory, and feminist postmodernismtoassess competingchims of immune function within a feminist context.
The primary function of all placentas is to act as an interface between the mother and fetus that allows, and even promotes, appropriate metabolic exchanges. This function is accomplished by bringing maternal and fetal blood into close apposition while maintaining separation of the maternal and fetal circulatory systems. Despite the common physiological functions shared by placentas, however, examination of placental morphology from different animal groups reveals a remarkable diversity of species-specific structural organization.The separation of fetal and maternal blood is always maintained by an elaboration of extraembryonic fetal tissues that cover fetal blood vessels. In some species the outermost layer of this fetal tissue, the trophoblast, is in direct contact with maternal blood. In many other species uterine tissues also contribute to the selective barrier separating the two blood systems. In addition to morphological variation among placentas of different animal groups, placentas undergo substantial structural modifications during pregnancy in a single species. In some animals different types of placentas function successively, or concurrently during a single pregnancy.As a result of these myriad details of placental structure, effective evaluation of fetal–maternal transfer of drugs must consider not only the components of the interhemal barrier of the fully developed placenta characteristic for each species, but also the placental structures functioning at each gestational stage of the fetus.
Immunology is one of the unique products of the darvinian age — born in the controversies of that fresh announcement that all species, including ourselves, were not static entities, but subject to change as a result of the vicissitudes of time and circumstance. Darwinism postulated an everchanging species defined by evolutionary necessity. In this scheme, the organism is not given, but evolves. Always adapting, it is always changing. Thus, this raises the core issue of organismal identity as a problem. Here, Alfred Tauber explores the concept of self and traces the development of the term from Metchnikoff's theory that immunity resides in the active pursuit of identity.
In this brief summary, we argue that many widely held beliefs about HLA-G are questionable. Recent research has led to a re-evaluation of many of the characteristics that were thought to make HLA-G unusual among the MHC class I molecules. First, contrary to reports suggesting that the gene encoding HLA-G exhibits marked polymorphism in some human populations, recent data have shown that the HLA-G gene has comparatively little polymorphism – a feature that might allow it to be expressed in the placenta without causing rejection by the maternal immune system. Second, although truncated forms of HLA-G are generated in the placenta, most of them are unlikely to have significant biological effects as they do not reach the cell surface. Third, the hypothesis that a major role of HLA-G is to prevent attack of the placenta by maternal natural killer cells is now the subject of renewed scrutiny. Finally, there is little evidence that the induction of expression of HLA-G is a major mechanism by which tumor cells avoid immune attack. HLA-G has once again become as mysterious as when it was discovered: an MHC class I molecule expressed at a challengingly extraordinary site – the immunologically uneasy interface between mother and fetus.
It is known that information that is not contained in the DNA sequence - epigenetic information - can be inherited from the parent to the offspring. However, many questions remain unanswered regarding the extent and mechanisms of such inheritance. In this Review, we consider the evidence for transgenerational epigenetic inheritance via the gametes, including cases of environmentally induced epigenetic changes. The molecular basis of this inheritance remains unclear, but recent evidence points towards diffusible factors, in particular RNA, rather than DNA methylation or chromatin. Interestingly, many cases of epigenetic inheritance seem to involve repeat sequences.
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