摘要:

AbstractA quantitative analysis of the volume of the darkly staining region of the posteromedial bed nucleus of the stria terminalis was performed on the brains of 26 age‐matched male and female human subjects. We suggest the term “darkly staining posteromedial” component of the bed nucleus of the stria terminalis (BNST‐dspm) to describe this sexually dimorphic region of the human brain. The volume of the BNST‐dspm was 2.47 times greater in males than in females. This region in humans appears to correspond to an area of the bed nucleus of the stria terminalis in laboratory animals that exhibits volumetric and neurochemical sexual dimorphisms, concentrates gonadal steroids, and is anatomically connected to several other sexually dimorphic nuclei. Furthermore, the bed nucleus of the stria terminalis is involved in sexually dimorphic functions, including aggressive behavior, sexual behavior, and gonadotropin secretion, which are also influenced by gonadal steroids. Therefore, it is possible that in human beings as well, gonadal hormones influence the sexual dimorphism in the BNST‐dspm and that this morphological difference, in part, underlies sexually dimorph

ISSN:0092-7317    

DOI:10.1002/cne.903020402

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe hypothesis that excitatory drive is transmitted monosynaptically from bulbospinal medullary respiratory neurons to spinal respiratory motoneurons was tested by an ultrastructural analysis of the phrenic motoneuronal pool in the rat. Combined anterograde labeling of the principal inspiratory bulbospinal neuron population (ventral respiratory group) and retrograde labeling of the phrenic motoneuron pool demonstrated the presence of labeled synaptic profiles, indicating that at least some bulbospinal inspiratory neurons make monosynaptic contacts with phrenic motoneurons. The synaptic boutons of ventral respiratory group neurons that were labeled in the phrenic nucleus had asymmetrical membrane densities at sites of synaptic contact with labeled phrenic somal or dendritic profiles, supporting the notion that this bulbospinal pathway has excitatory contacts with phrenic motoneurons. The morphological types of labeled boutons included three of the eight previously identified bouton types in the phrenic nucleus (Goshgarian and Rafols:Journal of Neurocytology13:85–109, 1984), including the “S”‐terminal, the “NFs”‐terminal, and the “F”‐terminal. There was no conclusive evidence of labeled double synapses, indicating that this type of synaptic contact is not common in the intact

ISSN:0092-7317    

DOI:10.1002/cne.903020403

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe calcium ion plays an important role in some critical developmental events in the nervous system, such as neurulation and neurite elongation. Therefore, as the intracellular calcium‐binding proteins calbindin‐D28k(CaB) and parvalbumin (PV) may be expressed in these developmental events. Accordingly, the ontological expression of CaB and PV was examined immunocytochemically in the spinal cord and dorsal root ganglia (DRG) of the rat, in order to evaluate the relationship between CaB and PV expression, and other important developmental events.During the ontogenesis of the spinal cord, the CaB‐like immunoreactivity was mainly observed in the cell somata. The immunoreactive cells in the ventral horn of the cervical and thoracic, lumbar, and sacral segments first appeared at embryonic day (E)‐12, E‐13, and E‐14, respectively. However, these cells were not detected in the intermediate gray matter of the same segments at E‐14, E‐15, and E‐16, respectively, and in the dorsal horn at E‐14‐E‐15, E‐16, and E‐17, respectively. The peak of immunoreactive cells, both as to number and intensity, occurred in the perinatal period. However, from postnatal day (P)‐14 on, the number and intensity of the positive cells decreased, the adult levels being reached at P‐35.The PV‐like immunoreactivity was mainly detected in the fibers and punctata during the ontogenesis of the spinal cord. The immunoreactive fibers first appeared on the surface of the dorsal horn in the cervical and thoracic segments at E‐14, then entered the dorsal horn at E‐15, and reached the intermediate gray matter and ventral horn at E‐16. The first appearance of these fibers in the same areas of the lumbar and sacral segments occurred 1 day later than in the cervical and thoracic segments. During the perinatal period, the maximum content of PV‐like immunoreactive fibers, together with many punctata, was seen in the gray matter. However, between P‐14 and P‐17, most of them lost immunoreactivity rapidly, with the exception of the medial region of the intermediate gray matter, where the PV‐immunoreactive punctata remained up to the adult stage.In DRG neurons, both CaB and PV was expressed, but in different neurons. Neurons labeled with anti‐CaB and anti‐PV sera were first detected at E‐16 and E‐14, respectively. These neurons were large or medium‐sized in the prenatal period. Small neurons were also labeled with these sera after birth. Positive neurons of different sizes in DRG increased in number in the postnatal period. Up to P‐35, the expression of CaB and PV in DRG reached the adult levels.The appearance of and developmental changes in CaB‐like and PV‐like immunoreactivities in the spinal cord and DRG may be maintained during the neurogenesis of the immunoreactive reg

ISSN:0092-7317    

DOI:10.1002/cne.903020404

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractMotoneurons of adult frog spinal cord have been retrogradely labeled with the carbocyanine derivative diI. Spinal cords were then dissociated and the labeled motoneurons partially purified by centrifugation over a bovine serum albumin (BSA) density gradient. The resulting cell suspension was plated on a substrate of innervated muscle extracellular matrix (ECM) to which the motoneurons attached and extended processes. Labeled adult motoneurons survived for more than 4 weeks in a defined medium in the absence of added serum or growth factors. These cultures of adult motoneurons provide a favorable preparation for studying molecular factors that influence process outgrowth and synapse formation.

ISSN:0092-7317    

DOI:10.1002/cne.903020405

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractGABA and glutamate immunogold staining demonstrated that nerve cells of the thalamic ventrobasal complex (VB) of mice were positive exclusively for glutamate. None of the neuronal perikarya reacted the GABA antibody. By using alternate thin sections of the normal VB, it was also shown that large “specific” somatosensory and small corticothalamic terminals, both of which contained spherical synaptic vesicles, exhibited only glutamate‐like immunoreactivity. A third axonal type, containing flat‐ovoid synaptic vesicles, stained only for GABA.Seventy‐five days after coagulation of the vibrissal follicles in newborn mice, a characteristic multiplication of GABA positive axon terminals was observed. In addition, it was demonstrated that, similarly to modified cortical endings (Hámori et al.,J. Comp. Neurol.254:166–183, '86), many GABA positive terminals appeared as specific afferent endings, replacing the missing “specific” vibrissal afferents. This finding shows a remarkable plasticity of inhibitory GABA axons during developmental synaptogenesis and provides further evidence that the size, location, and the type of attachment of presynaptic terminals are dependent on their pos

ISSN:0092-7317    

DOI:10.1002/cne.903020406

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractIn this study, progressive developmental changes in the nucleus and associated organelles, including the nucleolus, coiled bodies, nuclear envelope, and nucleoplasm, of hamster facial motor neurons were characterized by two parallel analyses: ultrastructural and morphometric. Golden hamsters (Mesocricetus auratus) used for this series were the 14‐day fetus, newborn (<6 hr), and 1, 2, 3, 4, 5, 7, 9, 11, and 13 days postnatal ages, with 3 animals per group. Following anesthesia and perfusion fixation, facial nuclear groups were dissected and processed for electron microscopy. Electron micrographs and camera lucida tracings of nuclear profiles were collected and analyzed. The ultrastructural analysis revealed progressive changes in the nucleolus from a compact, segregated type to a reticulated form characteristic of actively protein‐secreting cells. Nucleolar microbodies and fibrillar centers were seen at all ages; the latter structures appeared to decrease in size and increase with age in the series. The nucleolus‐associated chromatin became less condensed, suggesting an increase in the incorporation of rDNA into the nucleolus proper. Coiled bodies, both free and attached to nucleoli, were found in varying frequencies. The nucleoplasm of neurons at the earliest stages contained large numbers of heterochromatin clumps, which decreased concomitantly with an increase in interchromatin granules and fibrils during the later stages. Nuclear envelope imaginations, polarized along one side of the nucleus, increased throughout the developmental period examined. These changes occurred in concert with a 61% increase in nuclear size and a 47% increase in the length of nuclear envelope. The sequence of nuclear changes observed during this early period of normal facial neuronal growth completes the study of a series of distinctly defined cytomorphic events in this cell type, the lability of which can be experimentally tested for their functional roles in neuronal develo

ISSN:0092-7317    

DOI:10.1002/cne.903020407

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractIntracellular labelling of locust intersegmental interneurones with lucifer yellow or horseradish peroxidase was carried out in combination with light and electron microscope immunocytochemistry by using an antibody raised against gamma amino butyric acid (GABA). Fifteen percent (four out of 27) of intracellularly stained interneurones showed GABA‐like immunoreactivity. This is in agreement with previous physiological observations that 20% of the interneurones in this population make inhibitory output conceptions in the metathoracic ganglion. GABA‐like immunoreactivity was also found in processes presynaptic to the interneurones in the mesothoracic ganglion. The presence of such immunoreactive inputs onto the intersegmental interneurones correlates well with physiological evidence that their receptive fields are in part shaped by direct input from GABA‐ergic spiking local interneu

ISSN:0092-7317    

DOI:10.1002/cne.903020408

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractTactile responses in the granule cell layers of the cerebellar hemispheres of rats are topographically arranged as a series of patches each representing a different region of the body surface. Previous observations had suggested that patches representing specific body parts recur in similar folial positions in different individuals; however, these relationships were not quantified. In this study we make inter‐animal comparisons of the detailed distribution of receptive fields in the granule cell layer of the crown of crus IIa by using physiological mapping techniques. The results suggest that maps from different individuals do, in fact, share several topological features. These include the regions of the body surface represented, the general proportions of these representations, the relative positions of patches representing the same body parts, and the organization of receptive fields within patches located in similar positions. The principal variability seen in these comparisons was in the detailed neighborhood relations between different patches. As a result of the analysis of the consistent and variable features of these maps, we propose and discuss a new role for these cerebellar regions in coordinating the acquisition of tactile sensory informatio

ISSN:0092-7317    

DOI:10.1002/cne.903020409

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe response of retinal microglial cells, which accompanies retrograde degeneration of ganglion cell axons and perikarya (induced by transection of the optic nerve), was studied in whole‐mounted rabbit retinae labeled enzyme‐histochemically for nucleoside diphosphatase (NDPase), which is a microglial cell marker.A few days after transection, the number of microglial cells/mm2, as well as their staining intensity, began to increase in the inner plexiform layer. The mosaic‐like distribution of the star‐shaped microglial cells present in the inner plexiform layer of a normal rabbit retina was preserved during ganglion cell degeneration. As in the normal retina, processes of individual cells never overlapped with those of neighboring cells in the inner plexiform layer because individual cells in the “degenerating” retina acquired shorter processes, i.e., the cells occupied a smaller territory compared to the normal retina.In the nerve fiber layer the number and staining intensity of NDPase‐labeled microglial cell processes (most of which are aligned in parallel with degenerating ganglion cell axons) transiently increased and returned to normal values by 5 months post‐transection.Microglial cells that are not detectably NDPase labeled in the outer plexiform layer of a normal rabbit retina acquire intense staining a few days after the nerve is cut. The functional significance of the increased NDPase activity in the plasma membrane of microglial cells during degeneration remains t

ISSN:0092-7317    

DOI:10.1002/cne.903020410

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe proportion of ganglion cells connected to the several central targets of the retinal projection varies in different species. In the frog, the retinotectal projection is clearly the largest branch of the optic pathway and the relative size of the tectally projecting population can be expected to be correspondingly great. However, there have been no studies aimed at quantifying the size of this population and at partitioning its contralateral and ipsilateral components. We injected the tectum with horseradish peroxidase (HRP) dried onto fine needles to count the numbers of retinal ganglion cells labeled by retrograde transport. The retinas were prepared as flat‐mounts to facilitate the cell counting. The tecta were injected either unilaterally or bilaterally in mirror‐symmetric loci. Specimens included completely normal frogs and frogs which had undergone unilateral optic nerve regeneration, although only normal retinas are presented in the current study. The retrograde transport interval was varied progressively (from 3 to 5 days), and single or multiple injection's of HRP were placed singly or as clusters, in order to increment the cell counts toward a level of saturation. Approximately 70.9% of the neurons in the ganglion cell layer could be labeled by this method. Correcting for the presence of displaced amacrine cells, estimated to comprise approximately 16% of the neurons in the ganglion cell layer (Scalia et al., '85,Brain Res. 344:267–280), we calculate that approximately 84.4% of the retinal ganglion cells project contralaterally to the optic tectum.Flat‐mounted retinas ipsilateral to unilaterally injected tecta of completely normal frogs were also examined for labeled cells. The results of injections in the rostrolateral, caudomedial, and caudolateral tectum were studied. We found that ipsilaterally labeled cells comprised no more than 2.3% of the overall population of ganglion cells in the ganglion cell layer. The ipsilaterally projecting cells were found in loci which were approximately mirror‐symmetric to the regions of maximal cell labeling in the contralateral retinas from the same animals. The ipsilateral population was always displaced toward the periphery of the retina with respect to the contralateral population, regardless of whether the contralateral locus was centered in the temporal, ventronasal, or dorsonasal sector of the retina. Because the ipsilaterally projecting ganglion cells form such a minor population, and because they exist in the monocular as well as the binocular parts of the retina, it seems likely that they may not play a significant role in visual function in

ISSN:0092-7317    

DOI:10.1002/cne.903020411

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY