摘要:

AbstractWe have studied the innervation of the developing cochlea by immunocytochemical staining of the cytoskeletal proteins, neurofilament (NF), and spectrin (brain spectrin and erythrocyte spectrin). NF immunoreactivity was seen in spiral ganglion cell bodies and their processes and in fibers of the intraganglionic spiral bundle (IGSB) on gestational day 16. NF immunoreactivity with monoclonal antibodies to NF160 and NF68 was present beneath both inner hair cells (the IHC) and outer hair cells (OHCs) on gestational day 20. NF200 immunostaining was located only in the IGSB and in fibers reaching the IHC, The first NF200 immunoreactivity beneath the OHCs was seen in the basal turn at birth, NF labelling began to decrease on postnatal day 9 and its intensity became more like that of the adult. Brain spectrin immunostaining was first seen in the IGSB of the basal turn on gestational day 18. It reached the fibers between the spiral ganglion and the IHC on gestational day 20. Brain spectrin immunoreactivity was first seen beneath the OHCs in the basal turn at birth. It reached all the OHCs of the cochlea by postnatal day 4, and began to decrease 9 days after birth. Erythrocyte spectrin immunostaining was first observed during the second postnatal week, when it labelled spiral ganglion cells. The distribution of NF200 and brain spectrin immunoreactivity suggested that efferent innervation of OHCs is present at birth in the rat, and confirms previous studies showing the early efferent innervation of the OHCs of the mouse and the rat at birth, and the time lag between the appearance of the two spectrin isoforms during development.

ISSN:0092-7317    

DOI:10.1002/cne.903000202

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractIt is hypothesized that terminals containing γ‐aminobutyric acid (GABA) participate in presynaptic inhibition of primary afferents. To date, few convincing GAB A‐immunoreactive (GABA‐IR) axo‐axonic synapses have been demonstrated in support of this theory. The goal of this study is to document the relationship between GABA‐IR profiles and central terminals in glomerular complexes in lumbar cord of the monkey (Macaca fascicularis). In addition, the relationship between GABA‐IR profiles and other neural elements are analyzed in order to better understand the processing of sensory input in the spinal cord.GABA‐IR cell bodies were present in Lissauer's tract (LT) and in all laminae in the spinal gray matter except lamina IX, GABA‐IR fibers and terminals were heavily concentrated in LT: laminae I, II, and III; and present in moderate concentration in the deeper laminae of the dorsal horn, ventral horn (especially in association with presumed motor neurons), and lamina X. Electron microscopic analysis confined to LT and laminae I, II, and III demonstrated GABA‐IR cell bodies, dendrites, and myelinated and unmyelinated fibers. GABA‐IR cell bodies received sparse synaptic input, some of which was immunoreactive for GABA. The majority of the synaptic input to GABA‐IH neurons occurred at the dendritic level. Furthermore, the presence of numerous vesicle‐containing GABA‐IR dendrites making synaptic interactions indicated that GABA‐IR dendrites also provided a major site of output. Two consistent arrangements were observed in laminae I–III concerning vesicle‐containing GABA‐IR dendrites: (1) they were often postsynaptic to central terminals and (2) they participated in reciprocal synapses. The majority of GABA‐IR axon terminals observed contained round clear vesicles and varying numbers of dense core vesicles. Only on rare occasions were GABA‐IR terminals with flattened vesicles observed. GABA‐IR terminals were not observed as presynaptic elements in axo‐axonic synapses; however, on some occasions, GABA‐IR profiles presumed to be axon terminals were observed postsynaptic to large glomerular type terminals.Our findings suggest that a frequent synaptic arrangement exists in which primary afferent terminals relay sensory information into a GABAergic system for further processing. Furthermore, GABA‐IR dendrites appear to be the major source of input and output for this inhibitory system. The implications of this GABAergic neurocircuitry are discussed in relation to the processing of sensory input in the superficial dorsal horn and in terms of mecha

ISSN:0092-7317    

DOI:10.1002/cne.903000203

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractBy use of retrograde transport of horseradish peroxidase‐wheat germ agglutinin (HRP‐WGA) in combination with monoclonal antibodies against choline acetyltransferase (ChAT), we show that putative cholinergic inputs to the feline pontine nuclei originate from cells in the dorsolateral pontine tegmentum. These cells form a loosely arranged continuum that nevertheless may be subdivided into two groups on the basis of differences in cell morphology. One group consists of double‐labeled cells in the periventricular gray substance medial to, and partly merging with, the nucleus locus coeruleus. The other group consists of double‐labeled cells surrounding the brachium conjunctivum. In two cats with tracer injections in the pontine nuclei, 81% and 84%, respectively, of the retrogradely labeled cells in the dorsolateral pontine tegmentum are ChAT‐like immunoreactive (ChAT‐LI). In the same experiments, many ChAT‐LI cells, but no retrogradely labeled cells, are seen in the basal telencephalon.The pontine nuclei contain a plexus of thin ChAT‐LI fibers with varicosities resembling en passant as well as terminal boutons. These ChAT‐LI fibers appear to branch extensively and cover all parts of the pontine nuclei.Following injections of rhodamine‐B‐isothiocyanate (RITC) in the thalamus and Fluoro‐Gold in the pontine nuclei and surrounding regions in the same animal, all retrogradely labeled cells in the dorsolateral pontine tegmentum are labeled with both tracers, whereas most cells in the paramedian pontine reticular formation are labeled either with RITC or Fluoro‐Gold. Thus it appears that all cells in the dorsolateral pontine tegmentum that project to the pontine nuclei also project to the thalamus.In analogy with findings by others in the dorsal lateral geniculate nucleus, we suggest that the putative cholinergic projections to the pontine nuclei may serve to modulate transmission of cerebellar afferent information in accordance with the behavi

ISSN:0092-7317    

DOI:10.1002/cne.903000204

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe time course of the development of connections between the visual cortex and the main subcortical visual structures, as well as intrahemispheric and interhemispheric connections, has been studied in the marsupial wallaby (Macropus eugenii) to compare its development with that of placental mammals. Pouch young are born prior to retinal innervation of the primary visual centers and spend a protracted period of development in the pouch, making them ideal for visual, developmental studies. Horseradish peroxidase conjugated to wheatgerm agglutinin was injected into either the presumptive visual cortex or the superior colliculus in young of varying ages.Thalamocortical projections from the dorsal lateral geniculate and lateral posterior nuclei reach the presumptive visual cortex between 12 and 15 days after birth. Descending cortical connections form later. Corticogeniculate axons are first detected in the geniculate and lateral posterior nucleus at 48 days after birth, while corticocollicular axons first reach the superior colliculus at 71 days and, by 81 days, have innervated the superficial layers.Intrahemispheric and interhemispheric connections form even later. By 99 days intrahemispheric axons from area 17 have accumulated in visual association areas but are yet to invade layers III and IV, their major termination zones in adult, while axons projecting back to area 17 have also reached their target area. At this time interhemispheric axons from area 17 have begun to accumulate in the opposite visual cortex, although they have not invaded the cortical layers. By 111 days cortical cells projecting to the opposite visual cortex are first labelled. These have a more widespread distribution in area 17 at 111 and 122 days compared to the adult, where they are confined to the 17/18 border.The results show that the marsupial wallaby has a timetable of similar sequence, but different relative timing, in. the formation of cortical connections compared to that of placental mammals. In the first half of the period between conception and eye opening, the timing in the wallaby precedes considerably that in placental mammals. Ascending connections from the thalamus develop relatively earlier in the wallaby but descending collicular connections are delayed until the same relative time that they appear in placental mammals.

ISSN:0092-7317    

DOI:10.1002/cne.903000205

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractEmbryonic mouse retinae transplanted to a variety of locations within the rostral midbrain of neonatal rats exhibit selective innervation of host visual nuclei when studied at maturity. Some of these nuclei (superior colliculus, nucleus of the optic tract, dorsal terminal nucleus) usually receive extensive transplant projections, others are innervated partially (dorsal division of the lateral geniculate nucleus, olivary pretectal nucleus, medial terminal nucleus), while a few (ventral division of the lateral geniculate nucleus, suprachiasmatic nucleus, intergeniculate leaflet) are not innervated at all. The selectivity of this innervation is largely independent of the transplant's position within the rostral brainstem, while the density of innervation of individual nuclei depends in part upon the proximity of the transplant to the nucleus and upon whether the host retinal projection to that nucleus is present or absent. These findings provide a foundation for further studies of the behavioral capabilities of retinal transplants, for developmental studies of factors responsible for the establishment of normal neural projections, and for examination of the immunological consequences of transplantation.

ISSN:0092-7317    

DOI:10.1002/cne.903000206

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractA detailed cytoarchitectonic atlas of the chinchilla cochlear nucleus complex was prepared in the transverse plane with the Nissl method. Subdivisions of the cochlear nucleus were defined on the basis of cell size, cell packing density, and, in some cases, on cytological features of cell types. In general, the chinchilla cochlear nucleus has an organizational plan similar to that described for other mammalian species. As in other rodents, the chinchilla has a large and well‐developed dorsal cochlear nucleus consisting of three distinct layers. The ventral cochlear nucleus consists of two distinct nuclear masses, a posterior nuclear group and an anterior nuclear group, each composed of several subdivisions, which are qualitatively similar to those described for other mammals. Thus it is now possible to compare detailed observations, such as tonotopic maps, in the chinchilla with findings from the analogous cell populations in other mammals, such as the cat with considerable precision. In the chinchilla, three cell groups, previously undescribed in mammals, have been defined and their counterparts in the cat identifie

ISSN:0092-7317    

DOI:10.1002/cne.903000207

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractRetrograde tracing, immunocytochemical, and histochemical methods were used to determine the manner in which different classes of trigeminal (V) ganglion cells respond to transection of their axons during infancy. Retrograde tracing with true blue (TB), histochemistry using the plant lectinBandieraea simplicifolia‐I (BS‐I), and immunocytochemistry using an antiserum directed against substance P (SP) were carried out in the V ganglion and V brainstem complex of normal adult rats. In the adult V ganglion, 11.9 ± 1.9% of the cells that sent axons into the infraorbital nerve (ION) contained SP‐like immunoreactivity (SPLI) and 26.9 ± 3.6% bound the lectin BS‐I. Only 2.7 ± 1.6% of ION cells were labelled by both the SP antiserum and BS‐I. Transection of the ION on the day of birth had very different effects upon primary afferent neurons containing SPLI and those labelled by BS‐I. We have previously shown that such lesions result in a significant expansion of the portion of SpC innervated by primary afferents containing SPLI and we have also provided data consistent with the proposal that ganglion cells recognized by an antiserum directed against SP are more likely than other primary afferent neurons to survive neonatal axotomy. In the present study, combination of retrograde tracing with TB and lectin binding histochemistry showed that cells recognized by BS‐I were selectively lost after neonatal ION transection. Only 14.2 ± 4.4% of the ION ganglion cells that projected into this nerve at the time of the lesion and that survived neonatal axotomy were BS‐I positive when the animals reached adulthood. Neonatal ION transection also resulted in a permanent reduction in the density of BS‐I binding in SpC.Bandieraea simplicifolia‐I binding in the brainstem ipsilateral to the damaged nerve was almost completely gone within 1 day of the nerve transection and recovered only partially by the time the rats were 2 months of age. In alternate sections tested with the SP antiserum, there was a slight reduction in the density of SPLI in the deafferented SpC on postnatal days 4 and 5, but this change never approached that ob

ISSN:0092-7317    

DOI:10.1002/cne.903000208

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractIn the present study, the fluorescent tract tracing compound Fluorogold was used to study the afferents of the SNB (spinal nucleus of the bulbocavernosus), which is found in the ventromedial spinal grey and innervates penile muscles of the male rat. Fluorogold was iontophoretically injected into the SNB, which was located by recording antidromic activation of the motoneurons after stimulating the bulbocavernosus muscle, Retrogradely labeled cells were found in laminae I, V–IX, and area X of the lumbar spinal cord, suggesting segmental input to the SNB. Supraspinally, the greatest number of labeled cells were in the medulla oblongata, particularly in the lateral vestibular nucleus, gigantocellular reticular nucleus, and ventral and alpha divisions of the gigantocellular reticular nucleus. Labeled cells were also observed in the medullary raphe nuclei, the ventral medullary nucleus, and the spinal vestibular nucleus. In the pons, labeled cells were observed in the nucleus locus coeruleus, nucleus subcoeruleus, and caudal pontine reticular nucleus. No labeled cells were present in the cerebellum, rostral pons, mesencephalon, and cerebral cortex. The most rostral occurrence of labeled cells was in the medial parvicellular division of the hypothalamic para ventricular nucleus. These potential afferents to the SNB identified in male rats imply that the inputs to motoneurons that innervate sex‐specific muscles involved in male reproductive behavior may be similar to the inputs to lumbar motoneurons described in the female rat that innervate muscles involved in female sexual behav

ISSN:0092-7317    

DOI:10.1002/cne.903000209

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractAxonal sprouting and regeneration were studied in the land snailAchatina fulicafollowing a unilateral crush to the cerebral–buccal connective. Both normal projection patterns and changes induced by injury were examined with axonal filling techniques. As expected, most staining was lost shortly after the crush when filling across the lesion site. Much of this decrease is attributable to the direct disruption of fiber pathways, but evidence also indicates that a limited amount of retraction of some neurites occurred during the first week. A subsequent, gradual increase in the numbers of stained elements culminated in supernumerary counts of fibers in many pathways and in some novel labeling of cell bodies, Maximum numbers of supernumerary fibers usually occurred 21–28 days after the lesion. Most of these extra neurites and cell bodies subsequently disappeared, and by day 35 the appearance of projections generally returned to within the ranges observed in normal, unlesioned animals. Together the results demonstrate the extent of neuritic regeneration, sprouting, and retraction that occurs in vivo within the gastropod nervous system following injury. The study also indicates the usefulness of such in vivo approaches to understand the long‐term processes that contribute to the restoration of morphological and functional inte

ISSN:0092-7317    

DOI:10.1002/cne.903000210

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.903000201

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY