摘要:

AbstractIn order to study the visual thalamocortical connections in the sheep, horseradish peroxidase (0.3‐0.5 μ1 of a 30% solution) has been injected in the gyri marginalis, ectomarginalis medius pars medialis, ectomarginalis medius pars lateralis and ectosylvius caudalis. The results show that: (1) the dorsal lateral geniculate nucleus (LGNd) projects to the former three gyri. Dorsal parts of the LGNd project to caudal areas, whereas its ventral parts project to rostral areas of these gyri; medial parts of the LGNd project to the gyrus ectomarginalis medius pars lateralis, while lateral parts project to the gyrus marginalis; (2) the medial interlaminar nucleus (MIN) or pars geniculata pulvinaris of Rose ('42b) projects to the caudal part of the gyrus marginalis and to the gyrus ectomarginalis medius pars lateralis; (3) the pulvinar proper of Rose (PUL) projects to the caudal part of the gyrus ectosylvius caudalis whereas the rostral part of this gyrus receives input from the medial geniculate body.In relation to Rose's cytoarchitectonic study of the cortex of sheep (1942a) the present study has shown that the LGNd projects to both the area striata (gyrus marginalis + gyrus ectomarginalis medius pars medialis) and area occipitalis (gyrus ectomarginalis medius pars lateralis) of Rose, that the gyrus marginalis and the area occipitalis receive a second projection (from the MIN), and that the PUL projects beyond the area occipitalis to the area parietalis of Ro

ISSN:0092-7317    

DOI:10.1002/cne.901870202

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractGlutamic acid decarboxylase (GAD, EC 4.1.1.15), the enzyme which catalyzes the α‐decarboxylation of L‐glutamate to form the neurotransmitter γ‐aminobutyric acid (GABA), was localized immunocytochemically in neurons of rat neostriatum, pallidum and entopeduncular nucleus. A large amount of GAD‐positive reaction product was observed in both the pallidum and entopeduncular nucleus in light microscopic preparations and was localized ultrastructurally to axon terminals that surrounded dendrites and large somata. In the neostriatum the relative numbers of GAD‐positive axon terminals per unit area were substantially less than in the pallidum. GAD‐positive terminals predominantly formedsymmetricsynapses with somata, dendrites and spines, but a small number of them formedasymmetricsynapses with either dendrites or spines. The presence of GAD within these terminals is consistent with results of other investigations which have indicated that the striatopallidal and striatoentopeduncular pathways as well as neostriatal local circuit neurons and/or collaterals from neostriatal projection neurons, use GABA as a neurotransmitter.GAD‐positive reaction product was also localized within the somata and dendrites of neostriatal and pallidal neurons in colchicine‐injected preparations. The GAD‐positive somata in the pallidum were medium‐sized neurons and since such cells project to the substantia nigra, our results are in agreement with those from other studies which demonstrate a GABAergic, pallidonigral pathway. In the neostriatum, GAD‐positive somata were identified light microscopically as medium‐sized neurons with either round or fusiform shapes. Electron microscopic examinations also showed GAD‐positive reaction product within the perikaryal and dendritic cytoplasm of these neurons, as well as in dendritic spines. These findings are in accord with the results of studies which have indicated that medium‐sized, spinous neurons of the neostriatum give rise to a GABAergic, striatonigral pathway. The significance of GAD localization within these neostriatal neurons is discussed in relation to recent findings which show that substance P is contained within this same class of st

ISSN:0092-7317    

DOI:10.1002/cne.901870203

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractWe have studied the naso‐temporal division of the retinothalamic pathway of the cat by making large unilateral injections of horseradish peroxidase into the lateral geniculate nucleus. In confirmation of previous work, our retinal whole‐mounts show a distinct vertical decussation line separating the contralaterally projecting nasal retina from the ipsilaterally projecting temporal retina. The ipsilateral decussation line is quite sharp, while the contralateral decussation is somewhat more diffuse, with numbers of large cells extending a few degrees into the temporal retina. However, in contrast to the results of optic tract section, our material (demonstrating the thalamic component only) does not reveal any significant population of contralaterally projecting small cells across most of the temporal retina. The previous observation of approximately 200 μm of naso‐temporal overlap in the area centralis is confirmed here, and evidence is presented that this overlap may in crease at eccentricities above the horizontal meridian.Taken together with previously published data, this demonstration of the vertical decussation line has allowed us to estimate the relative inclinations of the major meridians of the cat

ISSN:0092-7317    

DOI:10.1002/cne.901870204

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractBy injecting one lateral geniculate nucleus with large amounts of horseradish peroxidase (HRP), we have determined the retinal distributions of contra‐ and ipsilaterally projecting retinothalamic ganglion cells in the Siamese cat. In accord with the data of others, we observe that large numbers of temporal ganglion cells, which normally send axons ipsilaterally, instead misproject to the contralateral thalamus. However, in contrast to the expectations raised by previous work, we do not find the Siamese defect to be a simple 20° shift of the naso‐temporal decussation line. Rather, there is intermingling of the crossed and uncrossed retinothalamic populations in the temporal retina, with a gradual increase in the proportion of ipsilaterally projecting ganglion cells as one moves temporally. Thus, the Siamese abnormality represents not only a temporal displacement of the retinothalamic decussation line, but also a smearing of the normally rather sharp division between regions of ipsilateral and contralateral projection.Cell size measurements and anterograde transport of H3‐proline confirm the HRP finding and suggest differential effects of the Siamese abnormality according to ganglion cell class. In particular, it appears that the large ganglion cells tend to misproject to a greater degree than the rest of the retinothalamic popu

ISSN:0092-7317    

DOI:10.1002/cne.901870205

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractA cerebello‐pulvino‐cortical and a retino‐pulvino‐cortical pathways were revealed in the cat by means of the horseradish peroxidase (HRP) method. The sites of termination of the cerebellofugal and retinofugal fibers in the pulvinar nucleus (Pul) were visualized by the use of the anterograde transport of HRP. The cerebello‐pulvinar fibers were found to arise mainly from the parvicellular region of the lateral cerebellar nucleus and to terminate contralaterally in a narrow area at the extreme dorsolateral edge of the Pul at the level of the stereotaxic frontal plane A‐7.0. The area of terminal ramification of the retino‐pulvinar fibers was seen as a thin sheet lying at the extreme lateral edge of the Pul through most of the rostrocaudal extent of the Pul, bilaterally with contralateral predominance. The cerebellorecipient area in the Pul did not seem to overlap with the retinorecipient Pul area; the former appeared to be contiguous ventrolaterally to the latter. The cerebellorecipient and retinorecipient Pul areas were also observed to be connected reciprocally with the cerebral cortical areas; the former was connected with the most posterior part of the area 20, and the latter wit

ISSN:0092-7317    

DOI:10.1002/cne.901870206

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractRetinas from mice of the C57BL/6 strain were sampled at frequent intervals from birth to postnatal day 33 to determine the numerical density of conventional and ribbon synapses within the inner plexiform layer (IPL) as a function of time. Synaptic arrays of the IPL were formed in three phases. During Phase I, from day 3 to day 10, conventional synapses were produced at a mean rate of 0.44 synapses/1,000 μm3/hour, but no ribbons were seen. During Phase II, from day 11 to day 15, ribbons formed at a rate of 0.38 ribbons/1,000 μm3/hour and conventional synapses were produced at a rate of 1.15 synapses/1,000 μm3/hour. Phase III began at day 15, the approximate time of eye opening in these animals, and was characterized by a sharp reduction in the rate of production of both ribbons and conventional synapses. During this phase ribbons achieved a final mean density of 113 ribbons/1,000 μm3and conventionals achieved a final mean density of 250 synapses/1,000 μm3. Serial synapses appeared in Phase II but remained at low densi

ISSN:0092-7317    

DOI:10.1002/cne.901870207

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractThe results from several experimental approaches lead to the following conclusions. The nucleus cuneiformis projects to at least lumbar levels of the spinal cord. Its axons course through the ipsilateral sulcomarginal and ventral funiculi to distribute within lamina VIII and adjacent portions of lamina VII. Neurons within the nucleus reticularis pontis (RP), particularly within more medial parts of the nucleus, project through comparable routes to the same laminae. In addition, however, neurons within the lateral and dorsolateral RP relay through the lateral and dorsolateral funiculi, ipsilaterally, and the dorsolateral funiculus, contralaterally. Axons could be traced from the dorsolateral tracts to laminae IV through VII, lamina X and, in some instances, to laminae I and II. Injections of the dorsolateral pons also label the intermediolateral cell column and an area presumed to be the sacral parasympathetic nucleus. Many of the neurons which contribute to the contralateral bundle are located adjacent to the ventral nucleus of the lateral lemniscus.The nucleus reticularis gigantocellularis projects mainly via the sulcomarginal, ventral and lateral funiculi to laminae VIII and adjacent portions of laminae VII. The nucleus reticularis gigantocellularis pars ventralis innervates the same laminae; but, in addition, projects heavily to laminae I and II, to lateral portions of laminae IV through VII, to laminae IX and X and to the intermediolateral cell column. Axons destined for laminae I and II, as well as IV through VII and X, traverse the dorsolateral funiculi as described for the cat by Basbaum et al. (1978). Neurons within the nucleus reticularis parvocellularis project to cervical levels, mainly through the ventral funiculi. In general our results show that reticulospinal projections are more complex than suggested by degeneration methods and that laminae I, II, lateral parts of laminae IV‐VII, laminae IX and X, as well as the intermediolateral cell column and sacral parasympathetic nucleus are targets of axons from specific area

ISSN:0092-7317    

DOI:10.1002/cne.901870208

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractBy the use of the retrograde transport of horseradish peroxidase (HRP), the projections from the thalamus to the amygdala were investigated in the rat and cat, with main emphasis on the former species. HRP was injected stereotactically by microiontophoresis in the various amygdaloid nuclei. Several control procedures including the use of different approaches for the introduction of the micropipette were undertaken to eliminate the possibility of misinterpretation due to uptake of the protein by adjacent structures or fibers en passant.The paraventricular and parataenial nuclei of the thalamus were found to project throughout the entire amygdaloid complex. The medial geniculate complex and the basal nucleus of the ventromedial complex (the thalamic taste relay) mainly project to the centromedial part of the amygdala. The basolateral nucleus is the main recipient of a hitherto undescribed bilateral thalamo‐amygdaloid pathway originating in the interanteromedial nucleus. The parafascicular nucleus projects to the central nucleus of the amygdala; in the cat mainly to the lateral subdivision of the central nucleus.The findings are discussed in relation to previous anatomical and electrophysiological studies centered on the amygdaloid complex. Special reference is made to the possible role of the thalamo‐amygdaloid connections in the conveyance of sensory information to the amygd

ISSN:0092-7317    

DOI:10.1002/cne.901870209

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractEmbryos immobilized with neuromuscular blocking agents for differing periods between 4.5 and 9 days of incubation had an increased number of motoneurons in the brachial and lumbar lateral motor columns. Treatment with α‐cobratoxin (α‐CTX) on days 4‐9 for instance, was able to prevent virtually all natural cell death during this period; control embryos had an average of 22,500 lumbar motoneurons on day 5.5, and 13,500 on day 10, whereas treated embryos had approximately 21,000 cells on day 10. Curare, α‐CTX, α‐bungarotoxin (α‐BTX) and botulinum toxin were all about equally effective in preventing cell death. Similar treatmentbegun afterday 12, however, had no effect on cell number. If even a partial immobilization was continued after day 10 (in embryos totally immobilized earlier) most of the excess neurons were maintained, in some cases right up to hatching, at which time the embryos died due to respiratory failure. In contrast, when administration of the immobilizing agents was stopped, allowing the embryos' motility to return to control levels, the excess neurons underwent a delayed cell death and total cell number fell to below control levels by days 16‐18.Limb muscles from embryos with exces motoneurons exhibited relatively normal differentiation and had acetylcholinesterase (AChE) stained endplates which were innervated. Following curare treatment the two wing muscles, anterior and posterior latissimus dorsi, were found to have an increased number of AChE‐stained endplates, whereas the only leg muscle examined quantitatively – the ischioflexorius (IFL) –did not; the IFL, did, however, have a markedly reduced variance in endplate distance, as well as other apparent differences suggesting an altered pattern of innervation.Our findings imply that the number of motoneurons undergoing natural cell death is closely related to muscle activity. Thus, functional interactions at the developing neuromuscular junction seem to be critical in controlling cell death. If a retrograde trophic factor is involved its action is somehow re

ISSN:0092-7317    

DOI:10.1002/cne.901870210

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY

摘要:

AbstractThe method of electron dense degeneration has been used to make a quantitative study of the projection from the habenula through the fasciculus retroflexus (FR) to the interpeduncular nucleus (IPN) in the rat. The IPN is a midline structure onto which the right and left fasciculi converge. In the rostral part of the IPN the fascicular axons from each side form synapses throughout the mediolateral extent of the ventral two‐thirds of the nucleus. In the caudal part of the IPN the fascicular axons from each side terminate to an equal extent in two discrete, parasagittal zones, situated one on each side in the mid‐mediolateral extent of the IPN. These zones contain clusters of neurons located along the course of a characteristic row of arterioles and venules penetrating the IPN from its ventral surface.In both rostral and caudal parts of the IPN the fascicular axons form single synaptic contacts with the dendrites of the interpeduncular neurons, but caudally, in the two parasagittal zones they also form crest synapses. Crest synapses are only found in this part of the IPN. In crest synapses two presynaptic terminals form markedly asymmetrical contacts with the parallel opposing sides of an attenuated dendritic appendage (the crest). After unilateral fascicular lesions only one member of a pair of axon terminals contacting a crest degenerates. After bilateral fascicular lesions, however, there are many instances in which both members of a crest pair degenerate. This indicates that the axon terminals from the right and left fasciculi are segregated at the level of the crests, in such a way that one terminal comes from the right fasciculus and one from the left.At longer survivals after unilateral or bilateral fascicular lesions the degeneration is completely removed, but crest synapses are still present, indicating that the presence of fascicular axons is not necessary for the maintenance of crests in the IPN.To investigate the effects of chronic deafferentation, the left fasciculus was destroyed and, after a survival of at least six weeks (sufficient for all degeneration to be removed) the right fasciculus was destroyed one day before killing. Under these conditions there are many crests in which both axon terminals show degeneration. The proportion of such doubly degenerating crest synapses is similar to that found after acute (1 day) bilateral lesions, indicating that axons from the right fasciculus have reinnervated sites formerly occupied by the left fasciculus. We conclude that during normal development there is some constraint which prevents both sides of a crest being innervated by axons from the fasciculus of the same side of the brain, but that this constraint is not effective after unilateral fascicular lesions in the ad

ISSN:0092-7317    

DOI:10.1002/cne.901870211

出版商:The Wistar Institute of Anatomy and Biology    

年代:1979

数据来源: WILEY