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... generalized tetrapod spermatozoon manifesting the shared features of basal lissamphibians (fbr example, Ast'ttph.us) and basal amniotes (Chelonia, Sphenodort) is illustrated in Figure 3. As it shares features of basal, extant tetfapods, delineation of this hypothetical ancestral tetrapod sperm is not unduly speculative. ...
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... amliotes, as it is present in all amniote classes. With the exception o[ squamates (Fig. l5C). it commences imme- diately behind the midpiece, as in turtles, Sphenodon r Healy, Jamieson 1992; Jamieson, Healy 1992; Fig. 11), Cuittrtm crocodylus and, Crocodylus.johnstoni (Jamieson 1995a: Jamieson et al. 19971' Fig. 12), ratites, non- passerines ( Fig. 138) and in mammals (Jamieson 1995a; Fi-es. 16, 17F, ...
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... birds, a conical acrosome vesicle penetrated almosl to its tip by a subacrosomal space whiih contains a rodlike perforatorium has been demonstrated ultra- strxcturally in the non-passerines: turkey, Meleagris gal- lopavo; rooster, Gallus domesticus (Fig. 13A); guinea fowI, Numida meleagris ( Thurston et al. 1987); mallard duck, Anas plotjrhynchos (Humphreys 1972); the quail Coturnbc coturnix (Humphreys 1972 Figs. 13J, 14). This has also been demonstrated in the ratites (palaeognaths) tinamou, Eudromia elegans ( Asa et al. 1986); ostrich, Stuthio camelus ( Baccetti et al. \991:' Soley 1993" ...
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... by a subacrosomal space whiih contains a rodlike perforatorium has been demonstrated ultra- strxcturally in the non-passerines: turkey, Meleagris gal- lopavo; rooster, Gallus domesticus (Fig. 13A); guinea fowI, Numida meleagris ( Thurston et al. 1987); mallard duck, Anas plotjrhynchos (Humphreys 1972); the quail Coturnbc coturnix (Humphreys 1972 Figs. 13J, 14). This has also been demonstrated in the ratites (palaeognaths) tinamou, Eudromia elegans ( Asa et al. 1986); ostrich, Stuthio camelus ( Baccetti et al. \991:' Soley 1993" and, emt:ul., Dromaius novaehollandiae ( Baccetti et al. 1991). ...
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... dense peripheral fibers, a basic amniote synapomorphy, and avian symplesiomorphy, have been observed in turkey, rooster and, though requiring VERTEBRATE SpEnu Pnvr-ocrxv / 321 confirmation, in guinea fowl (Thurston, Hess 1987); mallard duck (Humphreys 1972); panots ( Jamieson et al. 1995); doves such as Geopelia striata (Jamieson 1995a; Figs. 138, F, H); passerines stch as Grallina cyanoleuca (Fig. 13N); and in the anteriormost region of the principal.piece of ratite spermatozoa ( Asa et al. 1986;Baccetti et al. 1991;Soley 1993Soley , 1994. They are present in suboscine and the more apomorphic oscine passerines (Fig. 13N), being larger in the ...
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... and avian symplesiomorphy, have been observed in turkey, rooster and, though requiring VERTEBRATE SpEnu Pnvr-ocrxv / 321 confirmation, in guinea fowl (Thurston, Hess 1987); mallard duck (Humphreys 1972); panots ( Jamieson et al. 1995); doves such as Geopelia striata (Jamieson 1995a; Figs. 138, F, H); passerines stch as Grallina cyanoleuca (Fig. 13N); and in the anteriormost region of the principal.piece of ratite spermatozoa ( Asa et al. 1986;Baccetti et al. 1991;Soley 1993Soley , 1994. They are present in suboscine and the more apomorphic oscine passerines (Fig. 13N), being larger in the ...
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... et al. 1995); doves such as Geopelia striata (Jamieson 1995a; Figs. 138, F, H); passerines stch as Grallina cyanoleuca (Fig. 13N); and in the anteriormost region of the principal.piece of ratite spermatozoa ( Asa et al. 1986;Baccetti et al. 1991;Soley 1993Soley , 1994. They are present in suboscine and the more apomorphic oscine passerines (Fig. 13N), being larger in the ...
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... endonuclear canal is limited to the anterior 1 to 2 pm of the nucleus in rooster (Fig. 13A), guinea fowl, turkey and panot (Figs. 13J, 14) and the anterior third of the nucleus in the ostrich ( Baccetti et al. 1gg1). Restriction of the endonuclear canal to the anterior region of the nucleus in non-passerines and passerines may be a synapomorphy of these, homoplasic with crocodiles and derived ratites (emu, ...
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... endonuclear canal is limited to the anterior 1 to 2 pm of the nucleus in rooster (Fig. 13A), guinea fowl, turkey and panot (Figs. 13J, 14) and the anterior third of the nucleus in the ostrich ( Baccetti et al. 1gg1). Restriction of the endonuclear canal to the anterior region of the nucleus in non-passerines and passerines may be a synapomorphy of these, homoplasic with crocodiles and derived ratites (emu, ...
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... the non-passednes rooster (Figs. 138, C) and guinea fowl, the fibrous sheath has tansformed into an amorphous sheath (Thurston, Hess 1987). Less certainlv derived is adhesion of all nine dense fibers to rheir axonemal doublets (Figs. 13F, H, N, 14), a feature also seen in monotremes (Jamieson ...
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... birds are, as is commonly held, the sister group of crocodiles, their linear cristae (Figs. 13B, F, G, H, L, M) would indicate loss ol the concentric cristae of a com- mon ancestor with crocodiles. However, the sister group relationship with crocodiles was not supported in a cladistic analysis of sperm ultrastructure (Jamieson, Healy 1992t. Alrhough a bird-mammal sister group rela- tionship shown in the latter analysis is doubtfui, ...
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... the columbiforms, such as Geopelia striala (Fig. 13D) and Ocyphaps lophotes (Fig. 13K), even a perToratorium is absenl although. at leart in Ceopelia '\lrlala, some longitudinalll orientaled subacrosomal material is present cnd lacunae are present in the nucle- us which may represent a vestigial endonuclear canal (Jamieson 1995a). Both of these columbiforms appear plesiomorphic in ...
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... the columbiforms, such as Geopelia striala (Fig. 13D) and Ocyphaps lophotes (Fig. 13K), even a perToratorium is absenl although. at leart in Ceopelia '\lrlala, some longitudinalll orientaled subacrosomal material is present cnd lacunae are present in the nucle- us which may represent a vestigial endonuclear canal (Jamieson 1995a). Both of these columbiforms appear plesiomorphic in retaining a nuclear rostrum (Figs' 13D, ...
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... leart in Ceopelia '\lrlala, some longitudinalll orientaled subacrosomal material is present cnd lacunae are present in the nucle- us which may represent a vestigial endonuclear canal (Jamieson 1995a). Both of these columbiforms appear plesiomorphic in retaining a nuclear rostrum (Figs' 13D, k), ttroogtt it i. possible that its presence is a teversal' ...
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... narrots ( Jamieson et al. 1995; Fig. 14) and doves' str.r,ch is Ocyphaps lophotes and Geopelia striata' the fibrous sheath is lost (Fig. l3I). These taxa would there- fore orovide valuable controls in experimental investiga- tionJof the lunction of the fibrous ...
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... annulus is basic to bird sperm, being seen rn ratites, rooster (Fig. l3B), guinea fowl, and columbi- forms (Aia, Phillips 1987), but is apomorphically absent in oarrots ( Jamieson et al. 1995; Fig. ...
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... fibers are described as "tiny" for the rhea, are absent from the tinamou (Asa et a1. 1986), and are greatly reduced in columbiforms (Jamieson 1995a)' Very imall dense fibers are present only in the distal region of the midpiece in the rooster (Fig. 138) and mallard; dense fibers in turtle dove sperm disappear before maturation is complete (Asa, Phillips 1987), rhough they persist through a short region of the mid- piece in Geopelia striata (Jamieson 1995a; Fig. ...
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... in columbiforms (Jamieson 1995a)' Very imall dense fibers are present only in the distal region of the midpiece in the rooster (Fig. 138) and mallard; dense fibers in turtle dove sperm disappear before maturation is complete (Asa, Phillips 1987), rhough they persist through a short region of the mid- piece in Geopelia striata (Jamieson 1995a; Fig. ...
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... and sphenodontids). Origin of intermitochondrial material from mitochondria has been confirmed ontogenetically in the sperm of some squamates ( Oliver et al. 1996). Extramitochondrial dense bodies are almost limited to squamates but are seen, poorly developed, in the doves Geopelia striata (Jamieson 1995a; Figs. l3E, G) and Ocyphaps lophotes (Fig. 13L) in which, although appearing homoplasic, they may well indicate persistence of a genetic basis laid down in early ...
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Citations
... La morfología clásica de los espermatozoides de las 3 especies de serpiente de cascabel analizadas concuerda con lo descrito por Jamieson [7]. Al observar en el microscopio fotónico claramente una cabeza filiforme, un acrosoma en forma de una punta delgada, con una gran pieza media y una pieza terminal corta (Figura[10, 11]. ...
Currently there are few studies in collection and evaluation sperm snakes, studies using a Crotalus durissus as a model have focused on parameters such as sperm motility and ultrastructure, such reproductive parameters are considered a helpful tool for generating gene banks as an alternative conservation for endangered snakes. Because this is important do study in other semen parameters therefore, the objective of this study was to evaluate the response of sperm 3 species of rattlesnake's solutions to different osmolarity. It is noteworthy that the sperm of viper to differ mammalian morphology to present a different response to exposure to different osmolarity. Keyword— Crotalus, Osmolarity, Semen, Collection. Resumen— Actualmente son pocos los estudios realizados en colecta y evaluación de espermatozoides de serpientes, los estudios utilizando a Crotalus durissus como modelo, se han enfocado en parámetros como movilidad espermática y ultraestructura, dichos parámetros reproductivos son considerados una herramienta útil para la generación de bancos de germoplasma como una alternativa de conservación para serpientes en peligro de extinción. Lo que hace importante el realizar estudios en demás parámetros seminales, por lo tanto, el objetivo del presente estudio fue el evaluar la respuesta de los espermatozoides de 3 especies de serpientes de cascabel a soluciones de diferente osmolaridad. Cabe mencionar que el espermatozoide de víbora al diferir en morfología al de mamífero presentó una respuesta diferente a la exposición a diferente osmolaridad. Palabras claves—Crotalus. Osmolaridad, Semen, Colecta. I. INTRODUCCIÓN México cuenta con la mayor diversidad de serpientes cascabel, de las aproximadamente 42 especies descritas, el 92% se encuentra en el país siendo endémicas 25 de estas [1]. Cabe mencionar que las especies endémicas del país se encuentran en una categoría de riesgo en base a la normatividad mexicana vigente (SEMARNAT, 2010), C. transversus, endémica se encuentra en " en peligro de extinción " ; 7 también endémicas, en la categoría de " amenazada " , y 16 en " sujeta a protección especial ". De acuerdo con el sistema de categorización de la IUCN (2010), C. catalinensis está considerada como " critically endangered " , C. pusillus como " endangered " y C. stejnegeri como " vulnerable " , todas éstas, endémicas de México. Este grupo es particularmente vulnerable debido a su sensibilidad a cambios en el ambiente, además de ser un grupo con mala reputación al poseer un veneno inminentemente peligroso, el encuentro con humanos la mayoría de las ocasiones deriva en la muerte del ejemplar. Como resultado de esto, sus poblaciones han mermado. La fragmentación del hábitat ha causado el aislamiento de pequeñas poblaciones presentado endogamia y los problemas de concepción o apareamiento han restringido la reproducción en cautiverio [2]. Las técnicas de reproducción asistida son una herramienta para cambiar este escenario y promover programas de reproducción para la conservación de estas especies [3]. Por lo tanto, el Laboratorio de Investigación en Reproducción Animal, con la finalidad de poder utilizar el semen de serpientes de cascabel en técnicas de reproducción asistida empleó diluyentes como método de conservación [4], sin
... Interspecific variation in sperm morphology and size is influenced primarily by the method of fertilization (Franzen 1970), phylogeny (Jamieson 1999), and the degree of sperm competition (Birkhead and Møller 1998, Birkhead and Pizzari 2002, Pizzari and Parker 2009). Within species, basic sperm morphology is considered to be under stabilizing selection and highly conserved (Morrow and Gage 2001, Immler et al. 2008, showing high levels of heritability (Birkhead et al. 2005, Mossman et al. 2009). ...
Sperm competition, whereby sperm from multiple males compete to fertilize an egg, selects for adaptations that increase fertilization success. Because fertilization success is related to sperm number, size, and quality, both interspecific and intraspecific variation in these traits are predicted to correlate with the level of sperm competition. Specifically, species and individuals that experience high sperm competition are predicted to produce more sperm per ejaculate, produce longer sperm, and exert higher quality control, resulting in reduced numbers of morphologically abnormal sperm and reduced size variation via selection for the most successful sperm phenotype. However, the causes of sperm morphological and size variation and its consequences for sperm competition remain poorly understood, especially within species. We quantified variation in sperm morphology, size, and number in the Lance-tailed Manakin (Chiroxiphia lanceolata), a Neotropical suboscine passerine with a cooperative lek mating system. Although alpha-status males sire almost all chicks, the numbers of sperm produced per ejaculate by betas, nonterritorial adults, and subadult males were similar to those produced by alphas. Sperm counts declined with age in alphas, which may explain the decreased siring success of older alphas. Most ejaculates contained both normal helical sperm and abnormal sperm with rounded heads. The proportion of morphologically normal sperm per ejaculate was unrelated to social status or age. The coefficients of variation in sperm component length (head, tail, and total) both between and within alpha males were comparable to variation reported in asserines with low sperm competition. Total sperm length was shorter than in the majority of avian species studied to date, and cloacal protuberance and relative testis size were small. These results indicate low sperm competition, despite evidence for multiple paternity, or that sperm number rather than sperm morphology may be a major postcopulatory mediator of male reproductive success in this species. This work represents the first thorough quantification of intraspecific sperm variability in a suboscine passerine.
... Ultimately, recent ultrastructural analyses that infer evolutionary trends among reptiles have shown that some spermatozoa morphology characters may be synapomporphic among squamates . For example, Jamieson (1995) found that a single perforatorium may be a synapomorphy for squamates in their study of Iguania, and Jamieson (1999), Vieira et al. (2004), and Rheubert et al. (2010a) corroborated these data in their analysis in the within the Squamata. Also, the peripheral fibers associated with microtubule doublets 3 and 8 are grossly enlarged in squamates (Jamieson, 1995, 1999; Cunha et al., 2008), whereas in Sphenodon they are not (Healy and Jamieson, 1992). ...
We studied spermiogenesis in the Mediterranean Gecko, Hemidactylus turcicus, at the electron microscope level and compared to what is known within other Lepidosaurs. In H. turcicus germ cells are connected via cytoplasmic bridges where organelle and cytoplasm sharing is observed. The acrosome develops from merging transport vesicles that arise from the Golgi and subsequently partition into an acrosomal cap containing an acrosomal cortex, acrosomal medulla, perforatorium, and subacrosomal cone. Condensation of DNA occurs in a spiral fashion and elongation is aided by microtubules of the manchette. A nuclear rostrum extends into the subacrosomal cone and is capped by an epinuclear lucent zone. Mitochondria and rough endoplasmic reticulum migrate to the posterior portion of the developing germ cell during the cytoplasmic shift and the flagellum elongates. Mitochondria surround the midpiece as the anlage of the annulus forms. The fibrous sheath begins at mitochondrial tier 3 and continues into the principal piece. Peripheral fibers associated with microtubule doublets 3 and 8 are grossly enlarged. During the final stages of germ cell development spermatids are wrapped with a series of Sertoli cell processes, which exhibit ectoplasmic specializations and differing cytoplasmic consistencies. The results observed here corroborate previous studies, which show the conservative nature of sperm morphology. However, ultrastructural character combinations specific to sperm and spermiogenesis seem to differ among taxa. Further studies into sperm morphology are needed in order to judge the relevance of the ontogenic changes recorded here and to determine their role in future studies on amniote evolution.
... Figure 6.42 depicts a hypothesized pleisomorphic spermatozoon of the Amniota ( Jamieson 1999). This model sperm is very similar to that of sperm observed in the Chelonia, Crocodylia, and Sphenodontida ( Jamieson 2007). ...
... The presence of a distinct epinuclear lucent zone is also considered an autapomorphy for Squamata. Intermitochondrial dense bodies within the midpiece are also a probable apomorphy for squamates though they are also poorly developed (possible homoplasy) in some avian species ( Jamieson 1999). The subacrosome space or cone has a paracrystalline subarchitecture in squamates ( Butler and Gabri 1984;Carcupino et al. 1989;Jamieson 1999). ...
... Intermitochondrial dense bodies within the midpiece are also a probable apomorphy for squamates though they are also poorly developed (possible homoplasy) in some avian species ( Jamieson 1999). The subacrosome space or cone has a paracrystalline subarchitecture in squamates ( Butler and Gabri 1984;Carcupino et al. 1989;Jamieson 1999). Within the midpiece and the principal piece, a thick fibrous sheath, an apparent autapomorphy for non-sphenodontidan squamates, surrounds the axoneme. ...
... . 42 depicts a hypothesized pleisomorphic spermatozoon of the Amniota ( Jamieson 1999 ) . This model sperm is very similar to that of sperm observed in the Chelonia , Crocodylia , and Sphenodontida ( Jamieson 2007 ) . ...
... The presence of a distinct epinuclear lucent zone is also considered an autapomorphy for Squamata . Intermitochondrial dense bodies within the midpiece are also a probable apomorphy for squamates though they are also poorly developed ( possible homoplasy ) in some avian species ( Jamieson 1999 ) . The subacrosome space or cone has a paracrystalline subarchitecture in squamates ( Butler and Gabri 1984 ; Carcupino et al . ...
... The subacrosome space or cone has a paracrystalline subarchitecture in squamates ( Butler and Gabri 1984 ; Carcupino et al . 1989 ; Jamieson 1999 ) . Within the midpiece and the principal piece , a thick fibrous sheath , an apparent autapomorphy for non - sphenodontidan squamates , surrounds the axoneme . ...
... Additionally, the cell membrane of sperm may be simple and smooth or complex with varying adornments (e.g., Baccetti et al. 1974). p0040 The sperm of thousands of species have been described (primarily their ultrastructure), an effort that began in earnest in the 1960s (taxonomic reviews in Jamieson 1987aJamieson , 1987bJamieson , 1991aJamieson , 1999aJamieson , 1999bJamieson , 2000dJamieson , 2000e, 2005Jamieson , 2006Jamieson et al. 1995Jamieson et al. , 1999Scheltinga & Jamieson 2003a, 2006Rouse 2006). As noted by Morrow (2004): 'curiously, sperm morphology and ultrastructure is often the first (and sometimes the last) aspect of an organism's reproductive biology that is examined'. ...
This chapter reviews the current knowledge of variation in sperm morphology over several levels of biological organization: variation within males (both within and across ejaculates), among males, among populations, and among species, along with prevailing hypotheses addressing the adaptive significance of such variation. With regard to developmental mechanisms, three aspects of the physiology of sperm production serve to limit within-ejaculate variation in sperm phenotypes. First, the location of the testes and numerous aspects of testicular physiology of some taxa are clearly adaptations to maintain a homeostatic developmental environment for sperm. Second, developing spermatids may share cytoplasm. Third, sperm phenotypes are predominantly determined by testicular gene expression and hence the diploid genome of the male. Variation across ejaculates but within males can involve several traits including sperm numbers, overall semen quality and individual sperm quality. A special case of intramale variation in sperm form is found in species with sperm heteromorphism, in which different sperm forms are regularly produced by individuals. Differences among males in sperm morphology may derive from both genetic and environmental influences. Theories of condition-dependence basically posit that fitness-related traits are to a large extent dependent on an organism's underlying condition. Conclusions drawn from studies of sperm diversification between natural populations are reinforced by experimental evolution studies of sperm morphology in laboratory populations, as these studies address the evolvability of sperm traits and the nature of selection underlying sperm diversification. Furthermore, a discussion of evolutionary causes and consequences of sperm diversification, along with suggestions of fruitful areas for future exploration is presented.
... Sperm size and shape is highly diversified across animal taxa, ranging from tiny, amoeboid-shaped cells to long, flagellate cells (Jamieson, 1999;Jamieson et al., 1999). The adaptive significance of interspecific variation in sperm morphology has been examined by theoretical models (Ball & Parker, 1996), and comparative studies of different taxonomic groups (Gomendio & Roldan, 1991;Fitzpatrick et al., 2009). ...
Sperm morphology varies considerably both between and within species. The sperm of many muroid rodents bear an apical hook at the proximal end of the head. The curvature of the sperm hook varies greatly across species, however the adaptive significance of the sperm hook is currently not known. In wood mice the apical hooks intertwine to form sperm 'trains', which exhibit faster swimming velocities than single cells. Thus, it has been suggested that if sperm 'trains' were advantageous in a competitive situation, then the apical sperm hook might be an evolutionary product of selection via sperm competition. A comparative study of rodent species provided support for the hypothesis, and showed that species with higher levels of sperm competition had more reflected sperm hooks. Here, we tested this hypothesis at the intraspecific level. We quantified sperm hook morphology from seven house mouse populations, and found that interpopulation variation in hook curvature was not explained by variation in sperm competition risk. Furthermore, observations of ejaculated sperm revealed that sperm groups are not a common characteristic of mouse ejaculates. We suggest that selection for sperm attachment to the oviduct epithelium, and thus better retainment of sperm fertilizing potential, may provide a more general explanation of the evolutionary relationship between sperm competition risk and the curvature of the sperm hook among rodents, and provide a phylogenetic comparison among rodent species that supports our hypothesis.
... The ultrastructure of the C. durissus spermatozoon is described for the first time in the present work. The spermatozoon bears the characteristics recognized as synapomorphies of Squamata, which have already been specified in many previous works (Healy and Jamieson, 1994;Harding et al., 1995;Jamieson, 1995Jamieson, , 1999Oliver et al., 1996). Besides that, the following spermatozoon synapomorphies of Serpentes are present in C. durissus (Oliver et al., 1996;Jamieson, 1999): presence of dense collar, multilaminar membranes and extracellular tubules; reduction of the perforatorium base plate; and the unusual elongation of the midpiece. ...
... The spermatozoon bears the characteristics recognized as synapomorphies of Squamata, which have already been specified in many previous works (Healy and Jamieson, 1994;Harding et al., 1995;Jamieson, 1995Jamieson, , 1999Oliver et al., 1996). Besides that, the following spermatozoon synapomorphies of Serpentes are present in C. durissus (Oliver et al., 1996;Jamieson, 1999): presence of dense collar, multilaminar membranes and extracellular tubules; reduction of the perforatorium base plate; and the unusual elongation of the midpiece. According to Jamieson (1995), Oliver et al. (1996), Teixeira et al. (1999), Giugliano et al. (2002) and Vieira et al. (2004), the spermatozoa ultrastructure is a relevant source of characters for use in phylogenetic analysis of Squamata, although the number of species for which the gamete ultrastructure is described must be augmented. ...
The present study was undertaken to elucidate some aspects about the nature of the spermatozoon ultrastructure of Crotallus durissus using cytochemical methods. We also provide for the first time the ultrastructural description of this species spermatozoon. Cytochemical studies of spermatozoa have not been performed so far in the Serpentes, and species spermatozoon may prove helpful to better understand the reproductive biology of this group. Besides the synapomorphies of the Squamata and Serpentes, the C. durissus spermatozoon possess the following: circular acrosome tip; rounded perforatorium tip with a stopper-like basal modification; bilateral stratified laminar structures; central electron-dense structure within the proximal centriole; fibrous sheath extending until the level of the second mitochondrial ring; rounded mitochondria in cross-section, but with variable shape and organization in longitudinal and oblique sections, respectively; linear annulus; developed multilaminar membranes in the nuclear region and the midpiece. The formation of membrane filipin-sterol complexes occur sparsely along the head region, specially around the nucleus; the complexes were also present in the midpiece membrane and scarcely lining the flagellum. The complexes were present in the different layers of the multilaminar membranes. The ethanol-phosphotungstic acid (E-PTA) treatment relieved the presence of basic proteins in acrosome vesicle, pericentriolar material, peripheral fibers of the axoneme and fibrous sheath. The tannic acid technique revealed the microtubules of the centrioles and the axoneme; the extracellular tubules encircling the spermatozoa and those spread in the epididymal lumen were also observed. However, the immunocytochemistry assay using antibodies against alpha-tubulin and beta-tubulin, the primary microtubule monomers, does not support the existence of composition similarity between these tubular structures, since the extracellular tubules were not labeled by the antibodies. The results obtained in this work demonstrate that the utilization of electron microscopic techniques may provide relevant information to the study of ophidian reproductive biology, particularly in analyses concerning spermatozoal ultrastructure.
... Turtles may in fact be more derived and squamates may be more basal than previously appreciated (Lee et al. 2004). However, the structure of the spermatozoa of squamates appears to be highly derived relative to those of Chelonia (Jamieson 1999 and references therein). Second, the reptilian lineage most closely related to birds is still hotly debated (Feduccia 2002;Prum 2002) and we reconstruct patterns with birds sharing an immediate common ancestry with theropods and with a more basal archosaur lineage. ...
... The following characters, present in the spermatozoa of Le. koppesi (Leptotyphlopidae), T. reticulatus (Typhlopidae), Li. beui (Anomalepididae) and R. waitii (Typhlopidae) (Harding et al. 1995), were recognized (Healy and Jamieson 1994;Harding et al. 1995;Jamieson 1995Jamieson , 1999 as synapomorphies of Squamata: wholly prenuclear perforatorium; absence of endonuclear canals; sinuous mitochondria with linear cristae; intermitochondrial dense bodies; fibrous sheath penetrating anteriorly into midpiece; rounded nuclear shoulders; paracrystalline subacrosomal cone; axoneme forming the major axial component of the midpiece; short distal centriole; and reduced annulus. The presence of an epinuclear lucent zone, regarded as a synapomorphy of Squamata (Healy and Jamieson 1994;Harding et al. 1995;Jamieson 1995Jamieson , 1999, is confirmed in Le. koppesi, in T. reticulatus and in Li. beui, but it is not apparent in R. waitii (Harding et al. 1995). ...
... The following characters, present in the spermatozoa of Le. koppesi (Leptotyphlopidae), T. reticulatus (Typhlopidae), Li. beui (Anomalepididae) and R. waitii (Typhlopidae) (Harding et al. 1995), were recognized (Healy and Jamieson 1994;Harding et al. 1995;Jamieson 1995Jamieson , 1999 as synapomorphies of Squamata: wholly prenuclear perforatorium; absence of endonuclear canals; sinuous mitochondria with linear cristae; intermitochondrial dense bodies; fibrous sheath penetrating anteriorly into midpiece; rounded nuclear shoulders; paracrystalline subacrosomal cone; axoneme forming the major axial component of the midpiece; short distal centriole; and reduced annulus. The presence of an epinuclear lucent zone, regarded as a synapomorphy of Squamata (Healy and Jamieson 1994;Harding et al. 1995;Jamieson 1995Jamieson , 1999, is confirmed in Le. koppesi, in T. reticulatus and in Li. beui, but it is not apparent in R. waitii (Harding et al. 1995). ...
... The spermatozoa of Le. koppesi, T. reticulatus, Li. beui and R. waitii (Harding et al. 1995) bear the following characters, which are considered synapomorphies of Serpentes (Harding et al. 1995;Oliver et al. 1996;Jamieson 1999): presence of dense collar, multilaminar membranes and extracellular microtubules; reduction of the perforatorium base plate and the epinuclear lucent zone; and the unusual elongation of the midpiece. ...
We provide a detailed description of the sperm ultrastructure of three species of scolecophidian snakes, Leptotyphlops koppesi (Leptotyphlopidae), Typhlops reticulatus (Typhlopidae) and Liotyphlops beui (Anomalepididae), and make comparisons with the spermatozoa of Ramphotyphlops waitii (Typhlopidae) (Harding et al. 1995). All the species studied bear synapomorphies of Squamata and Serpentes. Among scolecophidian snakes, we identified eight polymorphic characters. Previous analyses of molecular and somatic morphological data provide equivocal solutions to the relationships among Anomalepididae, Leptotyphlopidae and Typhlopidae. A close relationship between Anomalepididae and Typhlopidae is corroborated by two characters of sperm ultrastructure, presence of an electron-dense structure inside the proximal centriole and rounded mitochondria in transverse sections of T. reticulatus, Li. beui and R. waitii, whereas the absence of the ridge on the acrosome surface of Le. koppesi and T. reticulatus support a closer relationship between Typhlopidae and Leptotyphlopidae. The differences observed in sperm ultrastructure within Typhlopidae suggest the existence of snake intrafamilial polymorphism. The sperm characters of blindsnakes contain significant phylogenetic information and may provide important data for snake phylogenetic reconstructions.
