Laura L Bruce

Creighton University, Omaha, Nebraska, United States

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Publications (22)71.98 Total impact

  • Laura L Bruce
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    Brain Behavior and Evolution 01/2012; 79(3):141-3. DOI:10.1159/000335343 · 4.29 Impact Factor
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    ABSTRACT: Pregnant rats were flown on the NASA Space Shuttle during the early developmental period of their fetuses' vestibular apparatus and onset of vestibular function. The authors report that prenatal spaceflight exposure shapes vestibular-mediated behavior and central morphology. Postflight testing revealed (a) delayed onset of body righting responses, (b) cardiac deceleration (bradycardia) to 70 degrees head-up roll, (c) decreased branching of gravistatic afferent axons, but (d) no change in branching of angular acceleration receptor projections with comparable synaptogenesis of the medial vestibular nucleus in flight relative to control fetuses. Kinematic analyses of the dams' on-orbit behavior suggest that, although the fetal otolith organs are unloaded in microgravity, the fetus' semicircular canals receive high levels of stimulation during longitudinal rotations of the mother's weightless body. Behaviorally derived stimulation from maternal movements may be a significant factor in studies of vestibular sensory development. Taken together, these studies provide evidence that gravity and angular acceleration shape prenatal organization and function within the mammalian vestibular system.
    Behavioral Neuroscience 03/2008; 122(1):224-32. DOI:10.1037/0735-7044.122.1.224 · 3.25 Impact Factor
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    David H Nichols, Laura L Bruce
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    ABSTRACT: To investigate the origins, migrations, and fates of Wnt-1-expressing cells in the murine hindbrain, mice carrying a Wnt-1 enhancer/lacZ transgene were observed from embryonic day (E) 8 through postnatal day 18. The transgene-stained ventricular layer waxed and waned prior to and following migrations from it. Stained cells migrated first external to the hindbrain as neural crest and then within it to form typical populations of the rhombic lip, as well as others not recognized as lip derivatives. Migrations originated in a temporally defined sequence, many from discrete rhombomeres. All moved first radially, then rostrally and/or ventrally, ipsi-, or contralaterally, in the mantle or marginal layers. These movements ultimately formed elements of several nuclei, aligned in four longitudinal bands: dorsal (including the gracile, cuneate, cochlear, and vestibular nuclei, plus cerebellar granular cells), dorsal intermediate (including trigeminal sensory, parvicellular reticular, and deep cerebellar nuclei), ventral intermediate (including lateral and intermediate reticular nuclei), and ventral (including the raphe obscurus and pontine nuclei). Transgene staining often persisted long enough to identify stained cells in their definitive, adult nuclei. However, staining was transient. The strength of the staining, however, was in its ability to reveal origins and migrations in both whole-mounts and sections, in single cell detail. The present results will permit analyses of the effects of genetic manipulations on Wnt-1 lineage cells.
    Developmental Dynamics 02/2006; 235(2):285-300. DOI:10.1002/dvdy.20611 · 2.67 Impact Factor
  • Laura L. Bruce
    Advances in Space Research 01/2006; 38(6):1015-1015. DOI:10.1016/j.asr.2006.09.024 · 1.24 Impact Factor
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    ABSTRACT: The relationship between vestibular stimulation and the distribution of peripheral vestibulocerebellar sensory fibers was studied in embryonic rats that developed in normal gravity (1G), 1.75G, 2.0G, or rotational environments from 10 to 20 days of gestation. Subsequently a fluorescent neuronal tracer was applied to the cerebellum, and allowed to diffuse retrogradely to the vestibular periphery. The distribution of labeled fibers and terminals in the posterior vertical canal and the utricle was analyzed. Sensory fibers in the rotation- and hypergravity-exposed embryos of the posterior semicircular canal and utricle displayed fewer long extending fibers and more terminal fields, suggesting faster rates of maturation as compared to the synchronous controls. Hypergravity exposures in the posterior canal caused increased terminal formation in the central zone of the cristae, and in the utricle caused increased terminal formation, including calyces, in the medial extrastriolar zone. These results show the importance of the vestibular environment in the development of peripheral vestibular innervation.
    Advances in Space Research 01/2006; 38(6-38):1041-1051. DOI:10.1016/j.asr.2006.03.002 · 1.24 Impact Factor
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    ABSTRACT: We believe that names have a powerful influence on the experiments we do and the way in which we think. For this reason, and in the light of new evidence about the function and evolution of the vertebrate brain, an international consortium of neuroscientists has reconsidered the traditional, 100-year-old terminology that is used to describe the avian cerebrum. Our current understanding of the avian brain - in particular the neocortex-like cognitive functions of the avian pallium - requires a new terminology that better reflects these functions and the homologies between avian and mammalian brains.
    Nature reviews Neuroscience 03/2005; 6(2):151-9. DOI:10.1038/nrn1606 · 31.38 Impact Factor
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    ABSTRACT: The standard nomenclature that has been used for many telencephalic and related brainstem structures in birds is based on flawed assumptions of homology to mammals. In particular, the outdated terminology implies that most of the avian telencephalon is a hypertrophied basal ganglia, when it is now clear that most of the avian telencephalon is neurochemically, hodologically, and functionally comparable to the mammalian neocortex, claustrum, and pallial amygdala (all of which derive from the pallial sector of the developing telencephalon). Recognizing that this promotes misunderstanding of the functional organization of avian brains and their evolutionary relationship to mammalian brains, avian brain specialists began discussions to rectify this problem, culminating in the Avian Brain Nomenclature Forum held at Duke University in July 2002, which approved a new terminology for avian telencephalon and some allied brainstem cell groups. Details of this new terminology are presented here, as is a rationale for each name change and evidence for any homologies implied by the new names. Revisions for the brainstem focused on vocal control, catecholaminergic, cholinergic, and basal ganglia-related nuclei. For example, the Forum recognized that the hypoglossal nucleus had been incorrectly identified as the nucleus intermedius in the Karten and Hodos (1967) pigeon brain atlas, and what was identified as the hypoglossal nucleus in that atlas should instead be called the supraspinal nucleus. The locus ceruleus of this and other avian atlases was noted to consist of a caudal noradrenergic part homologous to the mammalian locus coeruleus and a rostral region corresponding to the mammalian A8 dopaminergic cell group. The midbrain dopaminergic cell group in birds known as the nucleus tegmenti pedunculopontinus pars compacta was recognized as homologous to the mammalian substantia nigra pars compacta and was renamed accordingly; a group of gamma-aminobutyric acid (GABA)ergic neurons at the lateral edge of this region was identified as homologous to the mammalian substantia nigra pars reticulata and was also renamed accordingly. A field of cholinergic neurons in the rostral avian hindbrain was named the nucleus pedunculopontinus tegmenti, whereas the anterior nucleus of the ansa lenticularis in the avian diencephalon was renamed the subthalamic nucleus, both for their evident mammalian homologues. For the basal (i.e., subpallial) telencephalon, the actual parts of the basal ganglia were given names reflecting their now evident homologues. For example, the lobus parolfactorius and paleostriatum augmentatum were acknowledged to make up the dorsal subdivision of the striatal part of the basal ganglia and were renamed as the medial and lateral striatum. The paleostriatum primitivum was recognized as homologous to the mammalian globus pallidus and renamed as such. Additionally, the rostroventral part of what was called the lobus parolfactorius was acknowledged as comparable to the mammalian nucleus accumbens, which, together with the olfactory tubercle, was noted to be part of the ventral striatum in birds. A ventral pallidum, a basal cholinergic cell group, and medial and lateral bed nuclei of the stria terminalis were also recognized. The dorsal (i.e., pallial) telencephalic regions that had been erroneously named to reflect presumed homology to striatal parts of mammalian basal ganglia were renamed as part of the pallium, using prefixes that retain most established abbreviations, to maintain continuity with the outdated nomenclature. We concluded, however, that one-to-one (i.e., discrete) homologies with mammals are still uncertain for most of the telencephalic pallium in birds and thus the new pallial terminology is largely devoid of assumptions of one-to-one homologies with mammals. The sectors of the hyperstriatum composing the Wulst (i.e., the hyperstriatum accessorium intermedium, and dorsale), the hyperstriatum ventrale, the neostriatum, and the archistriatum have been renamed (respectively) the hyperpallium (hypertrophied pallium), the mesopallium (middle pallium), the nidopallium (nest pallium), and the arcopallium (arched pallium). The posterior part of the archistriatum has been renamed the posterior pallial amygdala, the nucleus taeniae recognized as part of the avian amygdala, and a region inferior to the posterior paleostriatum primitivum included as a subpallial part of the avian amygdala. The names of some of the laminae and fiber tracts were also changed to reflect current understanding of the location of pallial and subpallial sectors of the avian telencephalon. Notably, the lamina medularis dorsalis has been renamed the pallial-subpallial lamina. We urge all to use this new terminology, because we believe it will promote better communication among neuroscientists. Further information is available at http://avianbrain.org
    The Journal of Comparative Neurology 05/2004; 473(3):377-414. DOI:10.1002/cne.20118 · 3.51 Impact Factor
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    ABSTRACT: Many of the assumptions of homology on which the standard nomenclature for the cell groups and fiber tracts of avian brains have been based are in error, and as a result that terminology promotes misunderstanding of the functional organization of avian brains and their evolutionary relationship to mammalian brains. Recognizing this problem, a number of avian brain researchers began an effort to revise the terminology, which culminated in the Avian Brain Nomenclature Forum, held at Duke University from July 18 to 20, 2002. In the new terminology approved at this Forum, the flawed conception that the telencephalon of birds consists nearly entirely of a hypertrophied basal ganglia has been purged from the telencephalic terminology, and the actual parts of the basal ganglia and its brainstem afferent cell groups have been given names reflecting their now evident homologies. The telencephalic regions that were erroneously named to reflect presumed homology to mammalian basal ganglia were renamed as parts of the pallium, using prefixes that retained most established abbreviations (to maintain continuity with the replaced nomenclature). Details of this meeting and its major conclusions are presented in this paper, and the details of the new terminology and its basis are presented in a longer companion paper. We urge all to use this new terminology, because we believe it will promote better communication among neuroscientists.
    The Journal of Comparative Neurology 02/2004; 473:E1-E6. DOI:10.1002/cne.20119 · 3.51 Impact Factor
  • L L Bruce
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    ABSTRACT: Long-term space flight creates unique environmental conditions to which the vestibular system must adapt for optimal survival of a given organism. The development and maintenance of vestibular connections are controlled by environmental gravitational stimulation as well as genetically controlled molecular interactions. This paper describes the effects of hypergravity on axonal growth and dendritic morphology, respectively. Two aspects of this vestibular adaptation are examined: (1) How does long-term exposure to hypergravity affect the development of vestibular axons? (2) How does short-term exposure to extremely rapid changes in gravity, such as those that occur during shuttle launch and landing, affect dendrites of the vestibulocerebellar system? To study the effects of longterm exposures to altered gravity, embryonic rats that developed in hypergravity were compared to microgravity-exposed and control rats. Examination of the vestibular projections from epithelia devoted to linear and angular acceleration revealed that the terminal fields segregate differently in rat embryos that gestated in each of the gravitational environments.To study the effects of short-term exposures to altered gravity, mice were exposed briefly to strong vestibular stimuli and the vestibulocerebellum was examined for any resulting morphological changes. My data show that these stimuli cause intense vestibular excitation of cerebellar Purkinje cells, which induce up-regulation of clathrin-mediated endocytosis and other morphological changes that are comparable to those seen in long-term depression. This system provides a basis for studying how the vestibular environment can modify cerebellar function, allowing animals to adapt to new environments.
    Advances in Space Research 02/2003; 32(8):1533-9. DOI:10.1016/S0273-1177(03)90392-9 · 1.24 Impact Factor
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    ABSTRACT: The expression of ErbB4 mRNA was examined in dorsal thalamic regions of chicks and rats. In rats, ErbB4 expression was observed in the habenular nuclei, the paraventricular nucleus, intermediodorsal nucleus, the central medial thalamic nucleus, the posterior nucleus, the parafascicular nucleus, the subparafascicular nucleus, the suprageniculate nucleus, the posterior limitans nucleus, the medial part of the medial geniculate nucleus, the peripeduncular nucleus, the posterior intralaminar nucleus, the lateral subparafascicular nucleus, the lateral posterior nucleus, and all ventral thalamic nuclei. In chicks, expression was observed in the subhabenular nucleus, the dorsomedialis posterior nucleus, the dorsointermedius posterior nucleus, the nucleus of the septomesencephalic tract, and areas surrounding the rotundus and ovoidalis nuclei, including the subrotundal and suprarotundal areas, and all ventral thalamic nuclei. Most cells within ovoidalis and rotundus were not labeled. The similar pattern of afferent and efferent projections originating from ErbB4-expressing regions of the mammalian and bird dorsal thalamus suggests that ErbB4 hybridizing cells may be derived from a single anlage that migrates into multiple thalamic regions. Most neurons in the rotundus and ovoidalis nuclei of chick may be homologous to unlabeled clusters of neurons intermingled with ErbB4-expressing cells of the mammalian posterior/intralaminar region.
    Brain Research Bulletin 02/2002; 57(3-4):455-61. DOI:10.1016/S0361-9230(01)00678-5 · 2.97 Impact Factor
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    ABSTRACT: This paper outlines the development of the gravistatic sensory system of the ear. First, evidence is presented that a genetic program, for which major transcription factors have already been identified using gene expression studies and targeted mutagenesis, governs the initial development of this system. Second, the formation of sensory neurons and their connections to the brain is described as revealed by tracing studies and genetic manipulations. It is concluded that the initial development of the connections of sensory neurons with mechanosensory transducers of the ear (the hair cells) and the targets in the brainstem (vestibular nuclei) is also dependent on fairly rigid genetic programs. During late embryonic and early postnatal development, however, sensory input appears to be used to fine-tune connections of these sensory neurons with the hair cells in the ear as well as with second order vestibular neurons in the brainstem. This phase is proposed to be critical for a proper calibration of the gravistatic information processing in the brain.
    Advances in Space Research 02/2001; 28(4):595-600. DOI:10.1016/S0273-1177(01)00387-8 · 1.24 Impact Factor
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    ABSTRACT: Our anatomical and behavioral studies of embryonic rats that developed in microgravity suggest that the vestibular sensory system, like the visual system, has genetically mediated processes of development that establish crude connections between the periphery and the brain. Environmental stimuli also regulate connection formation including terminal branch formation and fine-tuning of synaptic contacts. Axons of vestibular sensory neurons from gravistatic as well as linear acceleration receptors reach their targets in both microgravity and normal gravity, suggesting that this is a genetically regulated component of development. However, microgravity exposure delays the development of terminal branches and synapses in gravistatic but not linear acceleration-sensitive neurons and also produces behavioral changes. These latter changes reflect environmentally controlled processes of development.
    Korean journal of biological sciences 10/2000; 4(3):215-21. DOI:10.1080/12265071.2000.9647547
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    ABSTRACT: The development of olivocochlear efferent axons and their contacts in the postnatal cochlea was studied after DiI applications to the olivocochlear bundle in the ipsilateral brainstem of rats from 0 to 10 days of age (P0-10). Light microscopic analyses showed that labeled axons reached the vicinity of inner hair cells by P0 and outer hair cells by P2. Electron microscopic analyses demonstrated that labeled immature efferent axons are present among supporting cells of the greater epithelial ridge as well as inner hair cells at P0. The first efferent contacts that contacted inner hair cells contained a few irregularly sized vesicles and, occasionally, mitochondria. Postsynaptic specializations within inner hair cells apposed to labeled efferent axons included subsynaptic cisterns, irregularly sized vesicles, and synaptic bodies. Similar features were present in unlabeled profiles, presumed to be afferents, indicating that immature efferent axons could not be reliably distinguished from afferents without positive labeling. Efferent axons synapsed with outer hair cells by P4 and had synapse-like contacts at the bases of Deiters' cells at P4 and P6. Contacts between afferents and efferents were observed frequently in the inner spiral bundle from P6. As they matured, efferent axon terminals contacting hair cells contained increasing numbers of synaptic vesicles and were typically apposed by well-defined postsynaptic cisterns, thus acquiring distinctive profiles.
    The Journal of Comparative Neurology 08/2000; 423(3):532-48. DOI:10.1002/1096-9861(20000731)423:33.0.CO;2-T · 3.51 Impact Factor
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    ABSTRACT: The development of olivocochlear efferent axons and their contacts in the postnatal cochlea was studied after DiI applications to the olivocochlear bundle in the ipsilateral brainstem of rats from 0 to 10 days of age (P0–10). Light microscopic analyses showed that labeled axons reached the vicinity of inner hair cells by P0 and outer hair cells by P2. Electron microscopic analyses demonstrated that labeled immature efferent axons are present among supporting cells of the greater epithelial ridge as well as inner hair cells at P0. The first efferent contacts that contacted inner hair cells contained a few irregularly sized vesicles and, occasionally, mitochondria. Postsynaptic specializations within inner hair cells apposed to labeled efferent axons included subsynaptic cisterns, irregularly sized vesicles, and synaptic bodies. Similar features were present in unlabeled profiles, presumed to be afferents, indicating that immature efferent axons could not be reliably distinguished from afferents without positive labeling. Efferent axons synapsed with outer hair cells by P4 and had synapse-like contacts at the bases of Deiters' cells at P4 and P6. Contacts between afferents and efferents were observed frequently in the inner spiral bundle from P6. As they matured, efferent axon terminals contacting hair cells contained increasing numbers of synaptic vesicles and were typically apposed by well-defined postsynaptic cisterns, thus acquiring distinctive profiles. J. Comp. Neurol. 423:532–548, 2000. © 2000 Wiley-Liss, Inc.
    The Journal of Comparative Neurology 07/2000; 423(3):532 - 548. DOI:10.1002/1096-9861(20000731)423:3<532::AID-CNE14>3.0.CO;2-T · 3.51 Impact Factor
  • Maha Y Khachab, Laura L Bruce
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    ABSTRACT: To determine the role of retinal axons in the development of the corticocollicular projection in mice, the lipophilic fluorescent dye, DiI, was used to compare the development of the cortical projections in phenotypically normal (C57BL/6J) mice to that of anophthalmic 129SV/CPorJ mice. Cortical axons in anophthalmic mice found their targets and established a laminar specificity similar to those of cortical axons in normal mice despite the absence of the retinal projection. Cortical axons in normal mice reached the superior colliculus before those in anophthalmic mice and also had a faster rate of growth within the colliculus. Unlike cortical axons in normal mice in early postnatal ages, those in anophthalmic mice formed a disperse bundle in the stratum opticum. Axons labeled by focal applications of DiI into area 17 terminated in a larger and more medial area in anophthalmic mice than in normal mice. Thus, retinal axons are not essential for cortical axons to reach the superior colliculus, but they may have a role in organizing the growth of later-arriving cortical axons. Furthermore, cortical axons can terminate in the superior colliculus with a coarse topography when retinal axons are absent, but they cannot form a topographically refined projection.
    Developmental Brain Research 06/1999; 114(2):179-92. DOI:10.1016/S0165-3806(99)00020-6 · 1.78 Impact Factor
  • Maha Y Khachab, Laura L Bruce
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    ABSTRACT: The location and development of the neurons that give rise to the corticocollicular projection were studied in C57BL/6J and 129SV/CPorJ anophthalmic mice. The first neurons that project to the superior colliculus appear in the subplate zone at E13 in C57BL/6J mice. Cortical plate neurons reach the colliculus about 2 days later. The appearance and development of these neurons are delayed by about 2 days in the anophthalmic strain.
    Developmental Brain Research 02/1999; 112(1):145-8. DOI:10.1016/S0165-3806(98)00159-X · 1.78 Impact Factor
  • Bernd Fritzsch, Laura L. Bruce
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    ABSTRACT: In our original application we proposed to investigate the effects of gravity on the formation of connections between the gravity receptors of the ear and the brain in rat pups raised in space beginning at an age before these connections are made until near the time of birth, when they are to some extent functional. We used the neuronal tracer, Dil, which could be applied to tissue obtained immediately after landing of the space shuttle, thus minimizing changes due to the earth's gravity. We hoped to determine whether the vestibular system develops in two phases, as do other sensory systems (such as the visual system). In these other systems the first phase of development is controlled genetically and the second phase is controlled by environmental stimulation. Our data collected strongly supports the idea that the vestibular system has these same two phases of development. The tissue obtained from the NIH.R1 experiment was of exceptionally high quality for our analysis. Therefore, we expanded our investigation into the ultrastructural effects of microgravity on vestibular development. For the sake of clarity we will subdivide our summary into two categories: (1) analysis of the branching pattern of axons between the vestibular nerve and the gravistatic receptors of the ear in flight and control animals, and (2) analysis of the branching pattern of axons between the vestibular nerve and the brain in flight and control animals.
  • Bernd Fritzsch, Laura L. Bruce
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    ABSTRACT: The lack of gravity is known to alter vestibular responses in developing and adult vertebrates. One cause of these altered responses may be changes in the connections between the vestibular receptor and the brain. Therefore, we propose to investigate the effects of gravity on the formations of connections between the gravity receptors of the ear and the brain in rat pups raised in space beginning at an age before these connections are made until near the time of birth, when they are to some extent functional. This investigation will make use of a novel technique, the diffusion of a lipophilic dye, Dil, in fixed tissue. This technique can be used to analyze the connections in specimens fixed immediately after landing of the space shuttle, thus minimizing changes due to the Earth's gravity. The evaluation of the data will enable us to detect gross deviations from normal patterns as well as detailed quantitative deviations.
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    ABSTRACT: We have reinvestigated the embryonic development of the vestibulocochlear system in mice using anterograde and retrograde tracing techniques. Our studies reveal that rhombomeres 4 and 5 include five motor neuron populations. One of these, the abducens nucleus, will not be dealt with here. Rhombomere 4 gives rise to three of the remaining populations: the facial branchial motor neurons; the vestibular efferents; and the cochlear efferents. The migration of the facial branchial motor neurons away from the otic efferents is completed by 13.5 days post coitum (dpc). Subsequently the otic efferents separate into the vestibular and cochlear efferents, and complete their migration by 14.5 dpc. In addition to their common origin, all three populations have perikarya that migrate via translocation through secondary processes, form a continuous column upon completion of their migrations, and form axonal tracts that run in the internal facial genu. Some otic efferent axons travel with the facial branchial motor nerve from the internal facial genu and exit the brain with that nerve. These data suggest that facial branchial motor neurons and otic efferents are derived from a common precursor population and use similar cues for pathway recognition within the brain. In contrast, rhombomere 5 gives rise to the fourth population to be considered here, the superior salivatory nucleus, a visceral motor neuron group. Other differences between this group and those derived from rhombomere 4 include perikaryal migration as a result of translocation first through primary processes and only then through secondary processes, a final location lateral to the branchial motor/otic efferent column, and axonal tracts that are completely segregated from those of the facial branchial and otic efferents throughout their course inside the brain. Analysis of the peripheral distribution of the cochlear efferents and afferents show that efferents reach the spiral ganglion at 12.5 dpc when postmitotic ganglion cells are migrating away from the cochlear anlage. The efferents begin to form the intraganglionic spiral bundle by 14.5 dpc and the inner spiral bundle by 16.5 dpc in the basal turn. They have extensive collaterals among supporting cells of the greater epithelial ridge from 16.5 dpc onwards. Afferents and efferents in the basal turn of the cochlea extend through all three rows of outer hair cells by 18.5 dpc. Selective labeling of afferent fibers at 20.5 dpc (postnatal day 1) shows that although some afferents are still in early developmental stages, some type II spiral ganglion cells already extend for long distances along the outer hair cells, and some type I spiral ganglion cells end on a single inner hair cell. These data support previous evidence that in mice the early outgrowth of afferent and efferent fibers is essentially achieved by birth.
    International Journal of Developmental Neuroscience 08/1997; 15(4-5):671-92. DOI:10.1016/S0736-5748(96)00120-7 · 2.92 Impact Factor
  • L L Bruce, B Fritzsch
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    ABSTRACT: Existing experimental embryological data suggests that the vestibular system initially develops in a very rigid and genetically controlled manner. Nevertheless, gravity appears to be a critical factor in the normal development of the vestibular system that monitors position with respect to gravity (saccule and utricle). In fact several studies have shown that prenatal exposure to microgravity causes temporary deficits in gravity-dependent righting behaviors, and prolonged exposure to hypergravity from conception to weaning causes permanent deficits in gravity-dependent righting behaviors. Data on hypergravity and microgravity exposure suggest some changes in the otolith formation during development, in particular the size although these changes may actually vary with the species involved. In adults exposed to microgravity there is a change in the synaptic density in the optic sensory epithelia suggesting that some adaptation may occur there. However, effects have also been reported in the brainstem. Several studies have shown synaptic changes in the lateral vestibular nucleus and in the nodulus of the cerebellum after neonatal exposure to hypergravity. We report here that synaptogenesis in the medial vestibular nucleus is retarded in developing rat embryos that were exposed to microgravity from gestation days 9 to 19.
    Journal of gravitational physiology: a journal of the International Society for Gravitational Physiology 08/1997; 4(2):P59-62.