摘要:

AbstractThe medullary and spinal efferents of the pedunculopontine tegmental nucleus and adjacent mesopontine tegmentum were investigated by employing (1) the anterograde autoradiographic methodology and (2) the retrograde transport of HRP and/or WGA‐HRP in combination with choline acetyltransferase immunohistochemistry.The anterograde experiments identified five descending pathways from the mesopontine tegmentum: (1)Probst's tract, which descends in the dorsolateral reticular formation in close relation to the nucleus of the solitary tract; (2) aventrolateral branchof Probst's tract that extends ventrolaterally alongside the spinal trigeminal nucleus; (3) aventromedial branchof Probst's tract that extends ventromedially through the gigantocellular field of the medulla; (4) themedial reticulospinal tract, which descends in parallel with the medial longitudinal fasciculus and turns ventrolaterally along the dorsal surface of the inferior olive to enter the ventrolateral funiculus of the spinal cord; and (5) acrossed ventromedial pathway, which descends in a ventral paramedian position through the magnocellular field of the medulla.The origins of these pathways reflected a rough lateral‐to‐medial topography of mesopontine tegmental cell groups. The parabrachial nucleus, situated furthest laterally, for example, projected primarily through Probst's tract and its ventrolateral branch. The pedunculopontine tegmental nucleus, midbrain extrapyramidal area, and the subceruleal region, situated more medially, projected descending axons largely through the ventromedial branch of Probst's tract. The pontine tegmental field, situated furthest medially and ventromedially, was the largest contributor to the medial reticulospinal tract.The retrograde transport experiments confirmed these general organizational features. The combination of retrograde transport with choline acetyltransferase immunohistochemistry established that the cholinergic pedunculopontine tegmental nucleus contributes a large portion to the mesopontine tegmental innervation of the medullary reticular formation. A much smaller number of cholinergic pedunculopontine neurons project as far as the spinal cord. Spinal projections from the mesopontine tegmentum originate largely from non‐cholinergic neurons of the midbrain extrapyramidal area, subceruleal region, Kölliker‐Fuse division of the parabrachial nucleus, and pontine tegme

ISSN:0092-7317    

DOI:10.1002/cne.902690302

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe organization of the auditory brainstem in adult, darkly pigmented ferrets was studied by using the retrograde transport of the lectin wheat germ agglutinin–horseradish peroxidase injected into one inferior colliculus. Retrogradely labelled neurons were found bilaterally in every nucleus of the auditory brainstem. The greatest number of labelled neurons was found in the cochlear nuclei contralateral to the injection site, the ipsilateral medial superior olivary nucleus, both lateral superior olivary nuclei, the ipsilateral ventral nucleus of the lateral lemniscus, both dorsal nuclei of the lateral lemniscus, and the contralateral inferior colliculus. Quantitative assessment of the projections from the cochlear nuclei showed that the number of contralaterally projecting neurons exceeded the number of ipsilaterally projecting neurons by about 50 to one. This ratio remained relatively stable over a wide range of volumes of injected lectin, whereas the absolute number of labelled neurons on each side varied by at least twofold for a constant volume of lectin. These results provide basic data on the ferret auditory system and demonstrate quantitatively some properties of the projections between the cochlear nucleus and the inferior colliculu

ISSN:0092-7317    

DOI:10.1002/cne.902690303

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractSurgical closure of an external naris of the rat from postnatal day 1 to day 30 results in a 25% decrease in the size of the ipsilateral olfactory bulb. Decreases in size must result from changes in either the number of neurons and/or glia, or their size or both. The present study was designed to quantify cell density (Nv) and number at various early postnatal ages in order to examine both normal patterns of maturation and sequences of change resulting from deprivation.Data from control subjects indicated that numbers of mitral cells remained constant while numbers of external tufted cells increased. Both relay cell populations exhibited increases in nuclear size suggestive of substantial postnatal differentiation. All interneuronal and glial populations increased in number, although differences in maturational patterns were observed between cell species. For example, light and dark subpopulations of granule cells differed in the timing of peak cellular density, and an inside‐to‐outside gradient of maturation was found for dark granule cells.Growth curves were generally similar in occluded and control pups until approximately day 20, when deprivation resulted in decreased number and nuclear area of external tufted cells and density and number of granule cells and their associated glia. Light granule cells were affected earlier than dark cells, perhaps because of their earlier arrival in the granule cell layer. The affected cell groups represent the last relay and interneuronal populations to be generated, perhaps explaining their particular susceptibility to the effects of experience. Most of the changes emerged late, thus suggesting that they represent the culmination of a series of experience‐induced changes within the maturing bulb. The observed effects may result from either altered cellular proliferation or death patterns (or both), alternatives now under investig

ISSN:0092-7317    

DOI:10.1002/cne.902690304

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe distribution of CGRP immunoreactivity in the cervical, thoracic, lumbar, and sacral levels of the human spinal cord was mapped at the light microscopic level with the aid of a rabbit‐generated antiserum against human calcitonin gene‐related peptide (CGRP). CGRP‐positive fibers formed a dense plexus in lamina I, II, the reticulated region of lamina V, and the tract of Lissauer at all spinal cord levels. The distribution of fibers showed some variations dependent on the cord level analyzed. At the light microscopic level, intervaricose fiber diameters consistantly measured 1.0 μm or less, and two types of CGRP varicosities were observed: a small (1 to 2 μm in diameter), relatively round profile and a larger, (3 to 4 μm in diameter) oval or oblong profile. At the electron microscopic level, immunostained varicosities contained a mixture of round clear vesicles and vesicles that contained dense cores. The CGRP immunoreaction product was often associated with vesicles containing dense cores. The reaction product was also seen associated with clear round vesicles or in the cytoplasmic matrix. Postsynaptic elements included dendritic spines, small and large diameter dendritic shafts and vesicle containing profiles. The presence of CGRP in the superficial dorsal horn of human spinal cord is highly suggestive of a role in primary afferent transmission as postulated in lower vertebrates. This study establishes the distribution of CGRP at four different spinal levels in human cord and will serve as a basis for future studies related to the pathologic conditions affecting sensory

ISSN:0092-7317    

DOI:10.1002/cne.902690305

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe distribution of cholecystokinin‐immunoreactive (CCK‐I) cell bodies was studied in the bed nucleus of the stria terminalis (BST) and amygdaloid complex of colchicine‐treated male and female rats. Immunoreactive cells were visualized in the BST medial amygdaloid (MeA), central lateral, basolateral, basolateral ventral, medial, intercalated, anterior cortical, and posterior cortical nuclei and the amygdalohippocampal zone. Several significant sex differences were observed. In the male, a dense aggregation of CCK‐I cell bodies was visualized in the MeA, especially in the dorsocaudal part and in the encapsulated part of the BST. In comparison, female rats had relatively fewer immunoreactive cells in both of these regions. In the lateral and basolateral amygdaloid nuclei, however, more CCK‐I cells were visualized in the female than in the male, but the difference was not statistically significant. These data provide characterization of a sexually differentiated CCK system. In addition, we observed that the number of CCK‐I cells in the BST and posterodorsal part of the MeA was substantially reduced after castration. The number of CCK‐I cells in female rats, however, was not significantly reduced after ovariectomy in any of the regions studied. These findings imply that the steroid regulation of CCK is sexually differentiated. The sexually dimorphic distribution of CCK‐I cells in areas that are targets of steroid hormones and regulate reproductive processes is consistent with the possibility that CCK participates in central integration of sensory and steroidal input that modulates reprod

ISSN:0092-7317    

DOI:10.1002/cne.902690306

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractWe have examined the origin and topography of cortical projections to area PO, an extrastriate visual area located in the parieto‐occipital sulcus of the macaque. Distinguishable retrograde fluorescent tracers were injected into area PO at separate retinotopic loci identified by single‐neuron recording.The results indicate that area PO receives retinotopically organized inputs from visual areas V1, V2, V3, V4, and MT. In each of these areas the projection to PO arises from the representation of the periphery of the visual field. This finding is consistent with neurophysiological data indicating that the representation of the periphery is emphasized in PO. Additional projections arise from area MST, the frontal eye fields, and several divisions of parietal cortex, including four zones within the intraparietal sulcus and a region on the medial dorsal surface of the hemisphere (MDP).On the basis of the laminar distribution of labeled cells we conclude that area PO receives an ascending input from V1, V2, and V3 and receives descending or lateral inputs from all other areas. Thus, area PO is at approximately the same level in the hierarchy of visual areas as areas V4 and MT.Area PO is connected both directly and indirectly, via MT and MST, to parietal cortex. Within parietal cortex, area PO is linked to particular regions of the intraparietal sulcus including VIP and LIP and two newly recognized zones termed here MIP and PIP. The wealth of connections with parietal cortex suggests that area PO provides a relatively direct route over which information concerning the visual field periphery can be transmitted from striate and prestriate cortex to parietal cortex. In contrast, area PO has few links with areas projecting to inferior temporal cortex. The pattern of connections revealed in this study is consistent with the view that area PO is primarily involved in visuospatial function

ISSN:0092-7317    

DOI:10.1002/cne.902690307

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractMotoneurones innervating the cat external anal sphincter muscle were labelled retrogradely following intramuscular injections with horseradish peroxidase (HRP). Labelled motoneurones were examined by correlative light and electron microscopy (LM and EM) with special regard to a qualitative and morphometric analysis of the axon terminals resident on the neuronal membrane.By LM, labelled motoneurones were (1) ipsilateral to the injections; (2) all in S1‐S2; (3) found only in the superior dorsomedial region of Onuf's nucleus; and (4) exhibited a broad spectrum of diameters (25–72 μm, mean 47.4 ± 11.3 μm).By EM, axon terminals on the neuronal membrane when classified according to size, vesicle shape, and synaptic complex ultrastructure conformed to the S‐, F‐, T‐, M‐, and C‐type terminals previously described for cat lumbosacral motoneurones. C‐terminals confirmed these sphincteric motoneurones to be skeletomotor. Pooled data from midnuclear sections through 15 random labelled motoneurones (20–64‐μm diameter) revealed that S‐ and F‐type terminals predominated, with numerically few M and C types. Notwithstanding their low frequency (0.3/100 μm membrane) C‐terminals contributed 1% of the mean areal coverage by terminals, which implies a potentially larger synaptic influence relative to other terminal types. Linear relationships occurred between terminal frequency (or cover) and motoneurone diameter. While motoneurones>40μm in diameter exhibited all five terminal types, labelled motoneurones ≤30 μ generally possessed only S‐, F‐, and occasional T‐type terminals, and in t

ISSN:0092-7317    

DOI:10.1002/cne.902690308

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe age‐related alterations in the number and size of alpha‐ and gamma‐motoneurons were studied in the medial gastrocnemius (MG) motor nuclei in rats at four ages: young (5 months), middle aged (10–13 months), old (26 months), and very old (31 months). Small volumes (0.1–0.5 μl) of 40% horseradish peroxidase (HRP) solution were injected into the cut MG nerve bilaterally by using glass micropipettes and a pressure injection system. The number, position, and soma size (average soma diameter) of MG motoneurons were determined by using photographic maps of each TMB‐stained section. The total number of myelinated axons was counted in seven MG nerves from the same animals.The average soma diameters in each MG nucleus were distributed bimodally; cells with average diameter greater than 21.0–24.0 μm were presumed to be alpha‐motoneurons and those with smaller diameters were presumed to be gamma. The mean number of presumed alpha‐motoneurons was significantly less in the old and very old groups as compared with the young and middle‐aged. In contrast, the number of presumed gamma‐motoneurons was the same across age groups. The mean average soma diameter of both alpha‐ and gamma‐motoneurons was smaller in the old animals. The apparent decrease in the total number of labeled motoneurons in old animals was also reflected in a decrease in myelinated axon counts. We conclude that there is a significant decrease in the absolute numbers of motoneurons in rats aged 26 months and older, with most of the decrease occurring among t

ISSN:0092-7317    

DOI:10.1002/cne.902690309

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractUtilizing the horseradish peroxidase retrograde tracing technique and the 2‐deoxy‐D‐glucose metabolic mapping technique, we have demonstrated in chickens the distribution of retinal ganglion cells that project to the lentiform nucleus of the mesencephalon (LM) and the retinotopic organization of the projection in the LM. Retinal ganglion cells labeled after a nearly complete injection into the LM were found in the four quadrants, distributed in a wide horizontal belt lying along both sides of the retinal equator and stretching from the temporal to the nasal retina. The HRP‐labeled cells, which appeared round or oval, ranged from 25 to 840 μm2in size with most in the smaller size range. Results of partial HRP injections into the LM and metabolic mapping patterns in the LM produced by stimulation of half the retina with horizontal visual motion suggest that there is an orderly mapping of the retina onto the LM. The inferior temporal quadrant projects to the rostrodorsal LM; the inferior nasal quadrant projects to the caudodorsal LM. The superior temporal quadrant projects to the middle and ventral LM, extending from the rostral to the caudal pole, whereas the superior nasal quadrant projects to a small zone in the caudal LM. The mapping of the retinal quadrants in the LM is remarkably similar to that reported in the optic tectum of birds. We suggest that a common embryological anlage with the optic tectum and the arrangement of retinal axons in the optic tract are important factors in establishing the retinotopic organization o

ISSN:0092-7317    

DOI:10.1002/cne.902690310

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe chemical differentiation of somatostatin (SS) neurons in rat neocortex was characterized by molecular biochemical and morphological methods. Northern (RNA) blotting indicates that regional distribution of SS mRNA correlates with the known distribution patterns of SS‐containing neurons in the adult, while similar analysis of poly (A)+ RNA isolated from telencephalon at various times postnatally shows an increase between P9 and P15, with a slight decrease in the adult. In situ hybridization with a probe specific to SS mRNA, and immunohistochemistry using antisera specific for the N‐terminally extended form of SS, SS28, and SS28(1–12), were used to detect neocortical neurons containing this mRNA or its translation product. The appearance of SS mRNA is coincident with detectable immunoreactivity for SS peptides. The expression of the SS gene by cortical neurons occurs in two waves. From P1 to P11, hybridizing neurons are predominant below the cortical plate in the developing infragranular layers. Immunohistochemical analysis of immunoreactivity to SS28 reveals a significant development of this neocortical system by late gestation (E20). At this point SS28(1–12), the predominant SS form detected, is mainly in neurons of the subplate, with less detectable immunoreactivity in the intermediate zone and cortical plate. By P2, neurons in the subplate exhibit detectable SS28 and SS28(1–12). Although immunoreactive perikarya are no longer detectable at P2 in the cortical plate or marginal zone, a very dense plexus of SS28(1–12) fibers is seen in the subplate, marginal zone, and intermediate zone; relatively few immunoreactive fibers are found in the cortical plate. By P12, a dramatic shift occurs; a large supragranular population of these SS neurons is observed by both mRNA and antibody methods, as is a subsequent decrease in number in the adult. The shift in immunoreactivity occurs with supragranular SS28‐containing neurons now prominent, and SS28(1–12)‐containing neurons and fibers greatly diminished. The number of neurons containing SS mRNA or SS28 immunoreactivity decreases from P12 to adult, when these neurons exhibit a bilaminar distribution. Neurons immunoreactive for SS28(1–12) are now sparsely distributed throughout the cortex, while SS28(1–12) fibers densely innerv

ISSN:0092-7317    

DOI:10.1002/cne.902690311

出版商:Alan R. Liss, Inc.    

年代:1988

数据来源: WILEY