摘要:

AbstractThe intrinsic connections of the superior temporal sulcus (STS) in the rhesus monkey were studied by anterograde and retrograde tracer techniques and correlated with a reevaluation of cortical cytoarchitecture. The polymodal region in the upper bank (area TPO) is divisible into four rostral‐to‐caudal architectonic sectors, exhibiting increasing degrees of laminar differentiation and cellularity as one proceeds caudally. These sectors, including the sulcal proisocortex (area Pro), are tied together in a sequence of reciprocal connections. Each rostrocaudal sector of area TPO also has reciprocal connections with the laterally adjacent area TAa, at the upper rim of the sulcus, and medially adjacent areas PGa and IPa, near the depth. A similar architectonic/ connectional organization exists for unimodal vision‐related cortex in the lower bank of the STS. Here a rostrocaudal sequence of reciprocal connections unites area Pro, rostral and caudal divisions of area TEa, and the extrastriate visual area OAa (MT). Area TEa also has reciprocal connections with adjacent segments of area TEm laterally, at the lower rim of the sulcus, and area IPa, medially, in the depth. In both upper and lower banks, caudal‐to‐rostral “for‐wardgoing” connections begin in supragranular layers of cortex and terminate in and around layer IV. Reciprocal, “backgoing” connections take origin from cells in infragranular layers and terminate mainly over the first layer of the caudally adjacent target zone. Orthogonally directed, “side‐to‐side” projections originate in both supra‐ and infragranular layers and terminate diffus

ISSN:0092-7317    

DOI:10.1002/cne.902900402

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe development of synapses and subsynaptic features in the neuropil of the ectostriatum, a visual projection area in birds, was examined ultrastructurally at 5, 10, 20, and 100 days posthatching. The maturation of the synaptic complex is accompanied by a variety of different dynamic processes. The number of synapses in ectostriatum and the number of specific synaptic types vary with age as does the constellation of subsynaptic structures. At day 5, before eye opening, the total number of synapses is 16% of the adult value. These synapses, unlike synapses seen at maturity, have indistinct synaptic contact zones and generally are associated with few synaptic vesicles. Synapse number increases continuously until 20 days of age, paralleled by a steady increase of the observed brain volume. The largest increase in synapse number takes place during the time of eye opening (i.e., between 5 and 10 days). This increase is mainly due to an increase of asymmetric synapses, the most common type in the neuropil of ectostriatum (90% of the synapse population). At day 20 the number of synapses has reached its maximum and remains high in adulthood. Synapses on spines are more prominent in younger animals than in adults. The percentage of presynaptic terminals involved in synaptic contact with more than one postsynaptic element (multiple synapses) shows a significant reduction from 12% to 4% early in development (between days 10 and 20). Presynaptic terminal size and postsynaptic density (PSD) length increase until 20 days of age. From day 20 to adulthood the PSD shows a 10% reduction in contact length, and the presynaptic terminal further increases in size by 27%. Therefore, the pre‐ and postsynaptic structures described above continue to develop after the number of synapses remains constan

ISSN:0092-7317    

DOI:10.1002/cne.902900403

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractIt has been proposed that calcitonin gene‐related peptide (CGRP) may serve as a major neuromodulator in visceral sensory pathways, but its exact role in the visceral sensory thalamus and cortex has not been determined. We therefore examined the distribution of CGRP‐like immunoreactive (CGRPir) innervation of the insular cortex and the parvicellular division of the ventroposterior nucleus of the thalamus (VPpc) in the rat by using immunohistochemistry for CGRP combined with retrograde transport of the fluorescent dye fluoro‐gold.Modest numbers of CGRPir fibers were distributed in the dysgranular and agranular insular cortex, but few were observed in the granular insular cortex. The density of CGRPir innervation increased caudally along the rhinal fissure and was considerably greater in the perirhinal cortex. When fluorogold was injected into the insular cortex numerous retrogradely labeled neurons were seen in the VPpc, but few of these were CGRPir. Retrogradely labeled CGRPir neurons were, however, seen in the ventral lateral and medial parabrachial (PB) subnuclei. Injection of fluoro‐gold into the perirhinal cortex (which is just caudal to the insular cortex along the rhinal fissure) resulted in many retrogradely labeled CGRPir neurons in the posterior thalamic region, including the subparafascicular, the lateral subparafascicular, and the posterior intralaminar nuclei.The VPpc was heavily innervated by CGRPir fibers but contained few CGRPir cell bodies. Injection of fluoro‐gold into the VPpc resulted in many retrogradely labeled CGRPir neurons in the external medial PB subnucleus bilaterally, but with a contralateral predominance. Smaller numbers of retrogradely labeled CGRPir neurons were also observed in the ventrolateral PB subnucleus, bilaterally with an ipsilateral predominance. These results suggest that CGRP may be a neuromodulator in the ascending visceral sensory pathways from the PB to the VPpc and the insular cortex, but not between the latter two s

ISSN:0092-7317    

DOI:10.1002/cne.902900404

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractAromatase‐containing neurons were immunohistochemically examined in rat brains by using a polyclonal antibody against human placental antigen. The antibody recognizes cytochrome P‐450 portion of aromatase, an enzyme converting androgen to estrogen. A large group of strongly immunoreactive cells was identified in the ventral pallidum, which extends caudally from the area surrounding the islands of Calleja. Other strongly or moderately stained cell groups were observed in the cerebral cortex, the amygdaloid area, the nucleus of the diagonal band, and the area anterior to the posterior commissure. Only a few stained cells were present in the medial preoptic region.These findings cast doubt upon the previous assumption, based on biochemical analysis of tissue samples, that the center of the aromatizing system is in the medial preoptic region. They indicate instead that most aromatase‐containing neurons of rats lie within the ventral pallidum ventromedially adjacent to the preoptic

ISSN:0092-7317    

DOI:10.1002/cne.902900405

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractWe utilized quantitative autoradiography to localize receptors for thyrotropin‐releasing hormone (TRH) and substance P in individual subnuclei of the rat nucleus tractus solitarii (NTS) and the dorsal vagal complex. Within the NTS, TRH receptor concentrations were highest within the gelatinosus and centralis subnuclei and the medial subnucleus rostral to the area postrema, moderate within the intermediate subnucleus and the medial subnucleus adjacent to the area postrema, and low within the ventrolateral and commissural subnuclei and the medial subnucleus caudal to the area postrema. In contrast, substance P receptor concentrations were high throughout the medial subnucleus, moderate in all other subnuclei medial to the tractus solitarius, and relatively low in subnuclei lateral to the tractus solitarius. The dorsal motor nucleus of the vagus contained high concentrations of both TRH and substance P receptors, whereas we observed low TRH and moderate substance P receptors in the area postrema. High TRH and moderate substance P receptors were observed in the adjacent hypoglossal nucleus. In addition, we compared the concentrations of TRH receptors between chloroform‐defatted and nondefatted tissue sections, and noted little effect of white matter tritium quench upon the observed TRH receptor concentrations. These results suggest that neurotransmitter receptors within the rat dorsal vagal complex are organized in a manner consistent with previous cytoarchitectural and hodological partitioning of the NTS and that the distribution of an individual neurotransmitter receptor in the NTS may correspond to the role of that transmitter in modulating autonomic funct

ISSN:0092-7317    

DOI:10.1002/cne.902900406

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractStereological estimates of the numbers of Purkinje cell nucleoli in human cerebellar cortex have been obtained from systematic random samples of tissue by using the fractionator. The estimates are unbiased by fixation, section thickness, or sampling errors and are independent of any assumptions about cell shape, size, or spatial orientation. Twelve brains from aged subjects of both sexes were examined.The average complement of nucleoli in four female brains (age range 71–93 years) amounted to 14.8 millions (with an observed coefficient of variation between subjects of 29%). For three male brains (76–91 years), the corresponding estimates were 15.7 millions (10%). No significant sex differences were found for these small samples. Five brains of unknown sex and age yielded values of 15.8 millions (18%).For the twelve brains examined, the total number of Purkinje cell nucleoli per cerebellum was found to be 15.4 millions (19%). Estimated numbers showed a significant positive correlation with cerebellar weights. The number of nucleoli in an individual cerebellum was obtained with high precision in as short a time as 4 ho

ISSN:0092-7317    

DOI:10.1002/cne.902900407

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractImmunoreactivity (IR) to calcitonin gene‐related peptide (CGRP) has recently been found in chick motoneurons. Bath application of this peptide causes an increase in surface acetylcholine receptor (AChR) density and cAMP level in cultured chick muscle cells. These results suggest a role for this peptide in the formation of synaptic specializations. In this study, we examined the development of CGRP IR in larvalXenopusmyotomal muscle in relation to synaptogenesis. Using an antiserum against CGRP, a monoclonal antibody against the p65 synaptic vesicle antigen and a fluorescence conjugate of α‐bungarotoxin, we followed the development of synaptic specializations with fluorescence microscopy in whole‐mount specimens. We found that the postsynaptic specialization in the form of AChR clusters was first detected in stage 22 (24 hour) embryos. The presynaptic specializations, including the synaptic vesicle clusters as evidenced by p65 antibody staining and CGRP IR, were first detected at stage 32 (40 hours). The appearance of these two presynaptic specializations followed the same time course. Subsequently, all three structures, the AChR clusters, CGRP IR, and synaptic vesicle clusters, were colocalized at the neuromuscular junction (NMJ). This shows that CGRP is unlikely to be involved in signaling the development of the postsynaptic apparatus. This premise is further examined in cultures ofXenopusmyotomal muscle cells. CGRP at concentrations up to 1 μM did not affect the number of AChR clusters, nor did it interfere with the formation of clusters induced by polycation‐coated beads. In contrast, an extract from the basement membrane ofTorpedoelectric organ promoted the formation of AChR clusters and interfered with the clustering activity of the beads. These results suggest that CGRP, an integral component of the presynaptic specialization, is not involved in signaling synaptogenesis a

ISSN:0092-7317    

DOI:10.1002/cne.902900408

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractNeurons containing somatostatin (SOM) are enriched in the dentate gyrus. We sought to establish the ultrastructural localization of this peptide in the dentate gyrus of the rat brain with a double‐bridged peroxidase‐antiperoxidase (PAP) method localizing antisera directed against somatostatin (SOM)‐28 and SOM‐281–12. Initial light microscopic observations confirmed that the majority of perikarya and thick varicose processes with intense SOM‐like immunoreactivity (SOM‐LI) were observed in the hilus. Fine varicose processes with SOM‐LI were found throughout all layers of the dentate gyrus but were most intense in the outer third of the molecular layer (ML), where an occasional perikaryon with SOM‐LI was seen.By electron microscopy, SOM‐LI was found in neuronal perikarya, dendrites, axons, and axon terminals. Two types of SOM‐containing perikarya were observed. The first type was small (6–10 μm), round or ovoid, and had a labeled cytoplasm with abundant Golgi complexes and a dense accumulation of PAP‐reaction product. The second type of perikarya was larger (11–16 μm) and had a more abundant cytoplasm than the first type, but the Golgi complexes did not appear labeled. Most (96% of 374) of the synapses on the SOM‐labeled perikarya and dendrites were from terminals without SOM‐LI which formed nearly equal proportions of asymmetric and symmetric junctions. The remainder of the presynaptic terminals contained SOM‐LI and made primarily symmetric synapses. Synaptic junctions from both unlabeled and labeled terminals were primarily on the shafts of the small (0.5–1.5 μm) SOM‐immunoreactive dendrites.The terminals with SOM‐LI (0.25‐1.3 μm) contained many small, clear vesicles and from zero to four large dense‐core vesicles. Terminals with SOM‐LI were associated (1) with one unlabeled perikaryon or dendrite (49% of 215 in the hilus; 76% of 326 in the ML); (2) with two unlabeled perikarya or dendrites simultaneously (5% hilus; 4% ML); and (3) with one SOM‐containing perikaryon or dendrite (6% hilus; 3% ML). In all three types of associations, synaptic contacts on perikarya were few while the majority were with small (distal) dendrites. Moreover, most of the terminals with SOM‐LI formed symmetric junctions or lacked membrane specializations but were without any apparent glial intervention in the plane of section analyzed. The remaining SOM‐labeled terminals (40% hilus; 17% ML) were without any apparent synaptic relations. However, a few of these terminals were in direct apposition to other terminals, some of which were also SOM‐immunoreactive. These results provide cellular substrates in the dentate gyrus for (1) direct synaptic modulation of SOM‐containing neurons by terminals with SOM as well as unidentified transmitters and (2) for primarily inhibition (symmetric synapses) of granule cells and interneurons by SOM‐containing terminals. Moreover, they support the concept that SOM‐containing neurons in the dentate gyrus may differ in terms of the involvement of the

ISSN:0092-7317    

DOI:10.1002/cne.902900409

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe nucleus paragigantocellularis in the ventrolateral medulla has been implicated in cardiovascular, pain, and analgesic functions; and it has also been found to be a major afferent to the pontine nucleus locus coeruleus. In the present study, afferents to the nucleus paragigantocellularis were identified in the rat by means of the retrograde tracers wheat germ agglutinin‐conjugated horseradish peroxidase or Fluoro‐Gold.Projections to the nucleus paragigantocellularis arise from a wide variety of nuclei with autonomic, visceral, and sensory‐related functions. Major afferents with consistent and robust retrograde labeling include most laminae of the spinal cord, the caudal lateral medulla, the contralateral paragigantocellularis, the nucleus of the solitary tract, the A1 area, the lateral parabrachialis, the Kölliker‐Fuse nucleus, the periaqueductal gray, and a preoculomotor nucleus in the ventral central gray, the supraoculomotor nucleus. Other notable afferents, seen only after large caudal injections into the nucleus paragigantocellularis, include the lateral hypothalamus, the paraventricular nucleus of the hypothalamus, and the medial prefrontal cortex. Minor afferents include the gigantocellular nucleus, the area postrema, the caudal raphe groups, the inferior colliculus, the A5 area, and the locus coeruleus.The projection from the supraoculomotor nucleus, not previously reported as an afferent to the ventrolateral medulla, was confirmed with anterograde tracing by means ofPhaseolus vulgaris‐leucoagglutinin. Iontophoretic deposits ofPhaseolus vulgaris‐leucoagglutinin into the nucleus of the solitary tract (commissuralis level) or into the periaqueductal gray also yielded terminal fiber labeling in the nucleus paragigantocellularis. Fibers from the supraoculomotor nucleus and the nucleus of the solitary tract were densest in the lateral aspect of the nucleus paragigantocellularis (corresponding to the rostroventrolateral reticular nucleus), while fibers from the periaqueductal gray were more medially located.Previous studies have defined inputs to the rostral ventrolateral medulla from the cochlear nucleus as well as from the colliculi. In the present study, deposits of wheat germ agglutinin‐conjugated horseradish peroxidase orPhaseolus vulgaris‐leucoagglutinin into the cochlear nucleus or the superior colliculus yielded only sparse anterograde labeling in the nucleus paragigantocellularis, but heavily labeled adjacent areas. The inferior collicular injections yielded strong but restricted anterograde labeling in the rostromedial paragigantocellularis, medial to the facial nucleus.These results indicate that the paragigantocellularis area receives inputs from diverse brain structures. Neurons in the nucleus paragigantocellularis afferent to the locus coeruleus, being distributed throughout this region, may provide a channel where several types of information are integrated and transmitted to the extensive locus coeruleus noradrenergic efferent network. Further studies are needed to determine which afferents to, and functions of, the nucleus paragigantocellularis are predominant in its regulation of the

ISSN:0092-7317    

DOI:10.1002/cne.902900410

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe expression of nerve growth factor (NGF) receptor in adult rat brain was studied by immunohistochemistry with a specific anti‐rat NGF receptor monoclonal antibody, 192‐IgG. Intense NGF receptor immunoreactivity (NGFRI) was found in structures known to be NGF responsive, including forebrain cholinergic neurons in medial septum, diagonal band of Broca, and basal nucleus of Meynert; central processes of neural‐crest‐derived sensory ganglion neurons and their innervated nucleus also contained such immunoreactivity. Distinct NGFRI staining was also found in many brain areas and cell types not known to be NGF responsive, including some hypothalamic regions, circumventricular organs, some areas related to the optic system, olfactory glomeruli, ependymal and subependymal cells in some locations, mesencephalic nucleus of the trigeminal nerve, cerebellar molecular layer, central linear nucleus, solitary tract and its nucleus, and inferior olive. The NGFRI in the circumventricular organs was further studied by in vivo labeling of125I‐ligands. Intravenously injected125I‐NGF, but not125I‐cytochrome c, was specifically accumulated in the area postrema. Biochemical study of the NGF receptor showed a major band of molecular weight of approximately 90 KDa in the area postrema, choroid plexus, median eminence, and medial septum with the relative content consistent with that seen by immunohistochemistry. No evidence of a truncated NGF receptor was observed. The results of this study suggest that NGF and its receptor have broader roles in adult mammalian brain than previ

ISSN:0092-7317    

DOI:10.1002/cne.902900411

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY