摘要:

AbstractThe numerical densities of granule and Purkinje cells in the cerebellar cortex of the rat were determined by stereological methods. The density of Purkinje cells in our fixed material was 1,018 ± 39 per mm2(mean ± s.e.m.) of Purkinje cell layer and that of granule cells 1.92 ± 0.03 × 106per μl of granular layer. The total area of Purkinje cell layer was 332 mm2and the volume of granular layer was 48 μl. The rat cerebellum therefore contains 3.38 × 105Purkinje cells and 9.2 × 107granule cells, from which there are 274 granule cells for each Purkinje cell. The density of granule cells and the density of parallel fibers in the molecular layer observed in a companion study indicate that the average length of a parallel fiber is arou

ISSN:0092-7317    

DOI:10.1002/cne.902740202

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe number of spines on an individual Purkinje cell in the cerebellar cortex of the rat was determined by stereological methods. Investigations were based on thin section electron micrographs, freeze fracture replicas, and horseradish peroxidase labeled cells. Purkinje cell dendritic spines in our embedded material had a mean length of 1.4 ± 0.05 μm and mean neck and head diameters of 0.22 ± 0.01 μm and 0.45 ± 0.02 μm, respectively. From these dimensions, an estimate of spine volume in embedded material of 0.132 μm3was obtained. The density of dendritic spines in our fixed material was 8.15 × 108or 7.24 × 108per μl of molecular layer from volume fraction and density per mm2, respectively. The number of spines per linear micron of Purkinje cell spiny branchlet was 17.2 from freeze fracture and 17.6 from horseradish peroxidase labeled dendrites. These all indicate that there are between 154,000 and 175,000 spines on the dendritic tree of each Purkinje cell, considerably more than previously reported fo

ISSN:0092-7317    

DOI:10.1002/cne.902740203

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractIn the present study, stereological techniques applied to electron micrographs of the molecular layer of the rat cerebellum have been used to estimate the number of parallel fiber synapses on the dendritic tree of a single Purkinje cell. Quantitative features of the parallel fiber to Purkinje cell dendritic spine synapses and of the parallel fibers were investigated as a preliminary to estimating the number of synapses. Parallel fiber to Purkinje cell synapses are flattened disclike structures with a mean axial ratio of 1.47 and a mean diameter of 319 μm in fixed tissue. The density of synapses in our fixed material was 8.17 × 108per μl of molecular layer. Determination of the length density of the synapses per unit area of micrograph indicated a synapse density of 8.03 × 108per μl. These densities give a total number of synapses per Purkinje cell of 1.74 × 105and 1.71 × 105, respectively. Estimation of the number of parallel fiber varicosities and of varicosity length gave a density of 9.31 × 108varicosities per μl of molecular layer and determining the mean number of parallel fiber to Purkinje cell synapses per varicosity gave a synapse density of 9.82 × 108per μl, equivalent to 2.09 × 105per Purkinje cell. The reasons why this estimate is likely to be too high are discussed. We conclude that there are some 175,000 parallel fiber synapses on an individual Purkinje cell dendritic tree in the cerebellar cortex of the rat, considerably more than previous

ISSN:0092-7317    

DOI:10.1002/cne.902740204

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe adrenergic system in the medulla oblongata of tree shrews was investigated by immunocytochemistry with an antibody against phenylethanolamine‐N‐methyltransferase. Two groups of adrenegic cells, which are equivalent to those of other species, were detected: Group C1 in the ventrolateral medulla and group C2 in the dorsomedial medulla.Adrenergic cells in C1 are located around the lateral reticular nucleus or between its subdivisions. They are mostly multipolar with branched processes. In group C2, some immunoreactive cell bodies smaller than those in C1 and many nerve terminals are found in the motor nucleus of the vagus, but most of the adrenergic cells and fibers are observed in the nucleus tractus solitarii. The cytoarchitecture of this nucleus resembles that described before for the rhesus monkey. In contrast to the rat, the subnucleus gelatinosus, which according to other authors receives cardiac and gastric afferents, is a prominent structure in immunocytochemically as well as conventionally stained sections. Adrenergic cell bodies and their fibers form a ring around this nucleus, but no immunoreactive structures are found within it. In the dorsomedial part of the nucleus tractus solitarii, adrenergic neurons are accumulated. They are often located in close proximity to blood vessels. Elongated immunoreactive neurons in the medial subdivision of the nucleus also seem to project in the direction of the dorsal area.Our data give new information about the adrenergic system in the medulla oblongata, especially in the nucleus tractus solitarii of the tree shrew, a species that provides a useful model of a small primate br

ISSN:0092-7317    

DOI:10.1002/cne.902740205

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe barn owl determines the directions from which sounds emanate by computing the interaural differences in the timing and intensity of sounds. These cues for sound localization are processed in independent channels originating at nucleus magnocellularis (NM) and nucleus angularis (NA), the cochlear nuclei. The cells of NM are specialized for encoding the phase of sounds in the ipsilateral ear. The cells of NA are specialized for encoding the intensity of sounds in the ipsilateral ear.NM projects solely, bilaterally, and tonotopically to nucleus laminaris (NL). NL and NA project to largely nonoverlapping zones in the central nucleus of the inferior colliculus (ICc), thus forming hodological subdivisions in which time and intensity information may be processed. The terminal field of NL occupies a discrete zone in the rostromedial portion of the contralateral ICc, which we have termed the “core” of ICc. The terminal field of NA surrounds the core of ICc and thus forms a “shell” around it. The projection from NL to the core conserves tonotopy. Low‐frequency regions of NL project to the dorsal portions of the core whereas higher‐frequency regions project to more ventral portions. This innervation pattern is consistent with earlier physiological studies of tonotopy. Physiological studies have also suggested that NL and the core of ICc contain a representation of the location of a sound source along the horizontal axis. Our data suggest that the projection from NL to the core preserves spatiotopy. Thus, the dorsal portion of NL on the left, which contains a representation of eccentric loci in the right hemifield, innervates the area of the right ICc core that represents eccentric right loci. The more ventral portion of the left NL, which represents loci close to the vertical meridian, innervates the more rostral portions of the right core, which also represents loci near the vertic

ISSN:0092-7317    

DOI:10.1002/cne.902740206

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractInteraural phase and intensity are cues by which the barn owl determines, respectively, the azimuth and elevation of a sound source. Physiological studies indicate that phase and intensity are processed independently in the auditory brainstem of the barn owl. The phases of spectral components of a sound are encoded in nucleus magnocellularis (NM), one of the two cochlear nuclei. NM projects solely and bilaterally to nucleus laminaris (NL), wherein interaural phase difference is computed. The other cochlear nucleus, nucleus angularis (NA), encodes the amplitudes of spectral components of sounds. We report here the projections of NA and NL to the lateral lemniscal nuclei of the barn owl.The lateral lemniscal complex comprises nucleus olivaris superior (SO); nucleus lemnisci lateralis, pars ventralis (LLv); and nucleus ventralis lemnisci lateralis (VLV). At caudal levels, VLV may be divided into a posterior (VLVp) and an anterior (VLVa) subdivision on cytoarchitectonic grounds. At rostral levels, the cytoarchitectural differences diminish and the boundaries between the two subdivisions become obscured. Likewise, our data from anterograde tracing studies suggest that at caudal levels the terminal fields of NA and NL remain confined to VLVp and VLVa, respectively. They merge, however, at rostral levels. The data also suggest that NL projects to the medial portion of the ipsilateral SO and that NA projects bilaterally to all parts of SO and LLv. Studies with the retrograde transport of horseradish peroxidase confirm these projections.

ISSN:0092-7317    

DOI:10.1002/cne.902740207

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe projection fields of spinocerebellar tracts arising from the lowest lumbar and sacral‐caudal segments were studied by the anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) in the cat.Injections of WGA‐HRP into these segments labeled mossy fiber terminals mainly in sublobules Ia‐Vf, lobule VI, and sublobules VIIb‐VIIIb. In the sagittal plane the labeled terminals were distributed in the apical part of the lobules. MOre than 90% of the total number were in the anterior lobe, of which 50–80% were in sublobules IIa and IIb. The labeled terminals were concentrated between 1.0 and 2.0 mm lateral to the midline. The results of injections following hemisections revealed that the projections are bilateral and that their quantity does not differ between the two sides. The projection fields in the horizontal plane were reconstructed from a series of cross sections through lobules I–III. The labeled terminals were distributed in two areas localized to the apical part of the lobules: area 1 located between 0.75 and 1.5 mm lateral to the midline in zone B of Voogd (the lateral part of the vermis) and area 2 located 2.0 mm lateral to the midline in zones C1–C3 (the intermediate region of the hemisphere).The present anterograde and previous retrograde HRP studies show that the spinocerebellar tract neurons in the medial part of lamina VII caudal to the L7 segment and in laminae V and VIII of sacral‐caudal segments project mainly to lobules I–V of the anterior lobe and to lobule VI, sublobule VIIb, and lobule VIII of the posterior lobe. The projections were most abundant in sub

ISSN:0092-7317    

DOI:10.1002/cne.902740208

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractWe have localized nicotinic acetylcholine receptors in the zebra finch brain by using three125I‐labelled ligands: alpha bungarotoxin and two monoclonal antibodies to neuronal nicotinic receptors (MAb 35 of Tzardos et al.,J. Biol. Chem., 250:8635–8645, ′81; and MAb 270 of Whiting and Lindstrom:J. Neurosci. 6:3061–3069, ′86). Unfixed brains from intact adult male and female zebra finches were prepared for in vitro autoradiography. Lowresolution film autoradiograms and high‐resolution emulsion autoradiograms were prepared for each of the three ligands.The major brain structures that bind all three of the ligands are hippocampus; hyperstriatum dorsalis; hyperstriatum ventralis; nucleus lentiformis mesencephali; nucleus pretectalis, some layers of the optic tectum; nucleus mesencephalicus lateralis; pars dorsalis; locus ceruleus; and all cranial motor nuclei except nucleus nervi hypoglossi.The major structures labelled only by [125I]‐alpha bungarotoxin binding included hyperstriatum accessorium and the nuclei: preopticus medialis, medialis hypothalami posterioris, semilunaris, olivarius inferior, and the periventricular organ. Of the song control nuclei, nucleus magnocellularis of the anterior neostriatum; hyperstriatum ventralis, pars caudalis; nucleus intercollicularis; and nucleus hypoglossus were labelled.The binding patterns of the two antibodies were similar to one another but not identical. Both labelled nucleus spiriformis lateralis and nucleus geniculatus lateralis, pars ventralis especially heavily and also labelled the nucleus habenula medialis; nucleus subpretectalis; nucleus isthmi, pars magnocellularis; nucleus reticularis gigantocellularis; nucleus reticularis lateralis; nucleus tractus solitarii; nucleus vestibularis dorsolateralis; nucleus vestibularis lateralis; nucleus descendens nervi trigemini; and the deep cerebellar nuclei. Lobus parolfactorius and nucleus vestibularis medialis were labelled by only MAb 270, whereas only MAb 35 labelled nucleus laminaris and the medial and lateral pontine nuclei.These data extend previous reports of cholinergic participation in the song system (Ryan and Arnold:J. Comp. Neurol. 202:211–219, ′81) to suggest that the zebra finch song system may contain several closely related nicotinic receptors. In several brain nuclei it appeared that certain anatomical portions of a nucleus or a certain class of neurons were specifically labelled. Furthermore, in certain cases, the labelling appeared to be clustered around Nissl‐stained cell nuclei, thus suggesting that the receptors are concentra

ISSN:0092-7317    

DOI:10.1002/cne.902740209

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractIn an attempt to identify putative neurotransmitters of rubrospinal neurons, immunocytochemical procedures were utilized in combination with retrograde tracing techniques in 15 adult male rats. Following injections of horseradish peroxidase (HRP) or wheat germ agglutinin conjugated to HRP (WGA‐HRP) into the spinal cord, midbrain sections were processed with a combined procedure that allowed visualization of both the retrograde tracer and one or more antigens including glutamate, glutaminase, and glutamatic acid decarboxylase (GAD). Initial colocalization studies demonstrated that glutamatelike and glutaminaselike immunoreactivities were cocontained within the same neurons. Following injections of HRP or WGA‐HRP into the spinal cord approximately 53% of retrogradely labeled neurons contained glutamate immunoreactivity. Triple‐labeling experiments indicated that glutamatelike immunoreactivity was colocalized with glutaminase immunoreactivity in retrogradely labeled rubrospinal neurons. Retrogradely labeled neurons did not contain GAD immunoreactivity. Moreover, triple labeling experiments verified that glutamatelike immunoreactive retrogradely labeled cells did not cocontain GAD immunoreactivity. These studies demonstrate that glutamate and its synthesizing enzyme, glutaminase, are present in some rubrospinal neurons and raise the possibility that a component of the rubrospinal projection may be glutamatergic. GAD, on the other hand, is not present in rubrospinal neurons. This finding supports the hypothesis that GABAergic neurons play a role as interneurons in the red nu

ISSN:0092-7317    

DOI:10.1002/cne.902740210

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe macaque neocortex is very densely innervated by serotonin‐containing fibers. The highest density of these fibers is in primary sensory regions such as the primary visual cortex. By using an antibody against serotonin, we analyzed the distribution and morphology of serotonin‐immunoreactive fibers and synapses in the primary visual cortex of the adult cynomolgus monkey. In addition, we quantified the laminar distribution of labeled varicosities and the distances between varicosities in single fibers. While serotonin‐immunoreactive fibers are found in all cortical layers, at least three bands of heightened density of innervation were readily recognized that were coincident with (1) layer IIIB to IVCα, (2) layer VA, and (3) layer VIB. Layer IVCα of area 17 contained more varicosities per unit area than any other sublayer. There was a high degree of variability in the intervaricosity distances along single fibers; more than half were longer than 10 μm.At the electron microscopic level, synaptic contacts were also observed throughout the entire thickness of area 17, with the highest frequency in layer IV. The labeled varicosities were packed with electron‐lucent synaptic vesicles and formed synaptic complexes with small, but conspicuous, postsynaptic densities. Dendritic shafts were the most common postsynaptic target of the labeled synapses. Among these characteristically slender postsynaptic shafts, profiles with structural features of both spiny and smooth dendrites were observed. The small diameter of most of the postsynaptic dendrites indicated that distal dendrites were preferentially contacted by serotonin‐immunoreactive varicosities. Although direct identification of the postsynaptic neurons will be required for complete characterization of this circuitry, the distribution of serotonin‐immunoreactive varicosities suggests that serotoninergic interactions in the primary visual cortex of the cynomolgus monkey are directed predominantly at the distal dendrites of granular and infragranular neurons rather than at targets in the suprag

ISSN:0092-7317    

DOI:10.1002/cne.902740211

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY