摘要:

AbstractThe morphology of certain Golgi‐stained cells was examined in the striate and peristriate cortex of the cat and in the striate cortex of the rhesus monkey. Neurons in layer III were selected on the basis of their characteristic vertical axon bundles, which are 20–150 μ in diameter and traverse layers II–VSelected neurons were examined under the electron microscope to characterize their synapses and to establish their postsynaptic targets. It was found that double bouquet cells form symmetrical or type II synapses. In the cat the postsynaptic membrane specialization was more extensive than in the monkey. After removing the Golgi precipitate from boutons of two cells in the cat, small pleomorphic and flattened vesicles were found in the boutonsEarlier suggestions that double bouquet cells make synapses preferentially with spines of apical dendrites could not be confirmed. Out of 66 boutons in area 17 of the cat, 86.4% formed synapses with dendritic shafts, many of them belonging to nonpyramidal cells, 9% with perikarya of nonpyramidal cells, and only 4.6% with spines. Out of 19 synapses examined in area 18, 74% were contacting dendritic shafts and the rest contacted spines. In the monkey 60% of a total of 35 double bouquet cell synapses made synapses with dendritic shafts. A different type of double bouquet cell with densely spiny dendrites is also described in layer IV of the monkey striate cortex. This neuron formed asymmetrical synapsesIt is suggested that layer III double bouquet cells with vertical axon bundles are probably inhibitory and act on other nonpyramidal cells and certain parts of pyramidal

ISSN:0092-7317    

DOI:10.1002/cne.901950402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractFollowing the injection of horseradish peroxidase into the ipsilaeral substantia nigra, 36 retrogradely labelled neurons in the striatum were characterized (in three rats) by Golgi staining and gold toning: each neuron was of the medium‐size, densely spinous type. Prior to the injection of horseradish peroxidase, two of the rats had had lesions placed in the ipsilateral motor cortex, the third rat had had a lesion placed in the ipsilateral frontal and prefrontal cortex. In the electron microscope, degenerating boutons of cortical neurons were found in asymmetrical synaptic contact with the spines of proximal and distal dendrites of all six of the identified striatonigral neurons that were studied. Some of the degenerating boutons were small (diameter 0.1–0.3 μ), while others were larger (1–2 μ). An individual dendrite of a striatonigral neuron was in synaptic contact with very few degenerating boutonsLocal axon collaterals im the striatum could be traced from two of the identified striatonigral neurons that received degenerating cortical boutons. These were studied in the electron microscope; their boutons formed symmetrical synapses with spines or dendritic shafts of other striatal neurons. The synaptic boutons contained large, clear, round and pleomorphic vesicles. The postsynaptic targets of these boutons morphologically resemble the dendrites of medium‐size spiny neuronsIt is concluded that afferents from the cortex make monosynaptic contact with the dendritic spines of medium‐size spiny striatonigral neurons and that such neurons have local axon collaterals in the striatum that form synapses with other sp

ISSN:0092-7317    

DOI:10.1002/cne.901950403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractThe high‐affinity uptake and release of glycine was studied in retinas ofXenopus laevis. In the toad and tadpole retina,3H‐glycine was accumulated by a population of cells located predominantly in the inner nuclear layer. When retinas preloaded with3H‐glycine were subjected to high K+‐concentrations, these retinas released large amounts of3H‐glycine by a Ca++‐dependent mechanism. The appearance and maturation of these putative glycinergic properties was followed during retinal development. Our results indicate that the high‐affinity uptake of glycine first appears around stage 33/34 whereas K+‐stimulated glycine release cannot be detected

ISSN:0092-7317    

DOI:10.1002/cne.901950404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractThe uptake, synthesis, and release of dopamine was studied in retinas ofXenopus laevi. In the tadpole and adult retina,3H‐dopamine is accumulated by cells located in the inner nuclear layer. Retinas preloaded with3H‐dopamine release this compound in response to high K+concentrations in the medium. This release is probably Ca++‐dependent as it is inhibited by Co++in the medium. Adult retinas are also capable of synthesizing3H‐dopamine from3H‐tyrosine. The appearance and maturation of these dopaminergic properties were followed during retinal development. Our data indicate that synthesis of dopamine can first be detected as early as stage 35/36 whereas uptake of dopamine first occurs at stage 43. K+‐stimulated release of preloaded3H‐dopamine from putative dopaminergic neurons is, however, not evident until stage 46. These results show that similar to the development of GABA‐ergic and glycinergic properties, the uptake, synthesis, and release mechanisms for dopamine emerge at different stages during retinal differentiation i

ISSN:0092-7317    

DOI:10.1002/cne.901950405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractThe cytoarchitecture of rat cingulate cortex is described. This includes the topographical distribution and layering patterns of Brodmann's areas 25, 32, 24, and 29a, b, c, and d. Area 24 is subdivided into a ventral area 24a and a dorsal area 24b, but an area 23 could not be identified between areas 24 and 29An analysis of Golgi impregnations in areas 32, 24, and 29 demonstrates that most neuronal types recognized in neocortical areas are also present in cingulate cortex. Besides typical and inverted pyramidal cells, there is a wide variety of nonpyramidal cells, including multipolar, bitufted, and bipolar cells. Small multipolar cells with small somata, a dendritic tree limited to one or two layers, sparse to moderately spinous dendrites and one of two varieties of short axonal trajectories are present in layers I and II of areas 32, 24, and 29d. Medium multipolar cells occur mainly in layers III and V; they have extensive dendritic trees which traverse three or more layers, moderately spinous dendrites, and an axonal plexus which either ascends or descends in the cortex. Large multipolar cells are also frequent in layers III and V; their extensive dendritic trees are essentially spine free and they have axons which form dense terminations, particularly in the layer above the one in which the cell body is locatedNeurons with elongated somata and a primarily vertical orientation of the dendritic tree are either bitufted or bipolar. Bitufted cells are most frequent in layers II and III of areas 32, 24, and 29d. These cells have dendritic trees which form “hourglass shaped” fields, dendrites which are moderately spinous, and axons which form either extensive horizontal and vertical projections or are “chandelier” in form. Bipolar cells, in contrast, are found in layers II–V; their sparsely spinous dendrites form narrow dendritic trees which are oriented vertically and extend across four or more layers, and their axons have the same vertical orientation as the dendritic treeIt is concluded that the form of the axonal arbors of nonpyramidal cells frequently mimics the extent and shape of their dendritic trees. Thus, small multipolar cells with limited, spherical dendritic trees may have axons which arch sharply and emit short, terminal branches. In contrast, medium and large multipolar cells have more extensive dendritic and axonal arbors which traverse two, three, or more layers. Of the fusiform cells, bitufted ones with their “hourglass” dendritic trees have extensive vertical and horizontally oriented axonal branches, while bipolar cells have narrow, vertically oriented dendritic and axonal arborsThe granular layers II–IV of area 29c contain the following types of neurons: small and fusiform pyramids, medium‐sized pyramids, large stellate cells, and medium multipolar cells. Fusiform pyramids are the only neurons unique to cingulate cortex. They are similar to the variety of pyramidal cells, but have an oval soma and only one basal dendrite which extends from the base of the cell body to arborize in layer IV. Large stellate cells differ from large multipolar cells in that they have densely spinous dendrites and axons which enter

ISSN:0092-7317    

DOI:10.1002/cne.901950406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractAsubstrate pathwayis a set of aligned guidance cues. (Such cues may be either cells or molecules). CNS substrate pathways can be demonstrated by transplanting axons to different starting locations. The stereotyped routes of transplanted axons will then demonstrate the locations of effective substrate pathways. To map CNS substrate pathways, Mauthner axons were transplanted to vaious unnatural locations along the CNS ofXenopusembryos. The routes of 24 experimental Mauthner axons were traced. Twenty‐one of these axons grew along parts of a stereotyped route extending in the ventral marginal zone from the caudal diencephalon through the spinal cord. This ventral substrate pathway ran the length of the basal plate; thus, we call it abasal substrate pathway. One experimental Mauthner axon grew along thealar substrate pathwaypreviously demonstrated by transplanted optic axons. The demonstrations of the alar and the basal substrate pathways suggest that during development a few long substrate pathways organize the overall layout of the long tracts of the CNS. We propose that the pattern of the earliest CNS substrate pathways is established in the neural plate and is topologically preserved as the neural plate rolls into a neural tube. This pattern may be manifest as the three‐dimensional organization of the early marginal zones formed by the peripheral processes (the endfeet) of certain developing ependyma and radial glia. Subsequently, the detailed anatomy of the axon tracts and the specific terminations of individual axons are probably determined by other local chemical c

ISSN:0092-7317    

DOI:10.1002/cne.901950407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractOn the basis of both morphological criteria and survival after ganglion cell axotomy, three populations of cells can be recognized in the ganglion cell layer of the chick retina. These are: (1) Irregularly shaped cells, which are not affected by axotomy and lack Nissl stain. They comprise about 5% of the total cell population and are probably glial cells. (2) Small cells which have a distinctive teardrop‐shaped perikarya, stain for Nissl substance, and are not affected by axotomy. They occur with a uniform density of about 4,000 cells/mm2across the entire retina and comprise 30‐35% of the total number of cells in the ganglion cell layer. It is suggested that these cells are displaced amacrine cells. (3) Cells which stain strongly for Nissl substance and disappear after axotomy. These cells comprise 60‐65% of the population of cells in this layer. The density of the latter cells varies throughout the retina. A high‐density region in the central area extends into the superior‐temporal retina. This high‐density region corresponds to a position in the lateral visual field extending into the inferofrontal field. The total number of these cells agrees with the reported number of the optic nerve fibres in the chick, (Rager and Rager, '78); therefore they are presumably ganglion cells. The size distribution of the presumptive ganglion cells varies in different parts of the retinaThe only previous study of the distribution and size of cells in the ganglion cell layer of the avian retina did not distinguish between ganglion cells and displaced amacrine cells (Binggeli and Paule, 1969). The present results are therefore likely to be a more accurate description of the total number of ganglion cells, the regional variations in their density, and the characteristics of their size than previous

ISSN:0092-7317    

DOI:10.1002/cne.901950408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractAntisera to the 150K‐dalton polypeptide of the bovine neurofilament triplet and chicken neurofilament antisera reacting with the 70K protein in isolated bovine brain filaments stained the same structures in rat cerebellum by immunofluorescence and peroxidase‐antiperoxidase methods, that is Purkinje cell baskets, thin nerve fibers in the lower half of the molecular layer and myelinated axons. The 150K bovine neurofilament antisera did not stain large motor neurons in the anterior horns of the spinal cord in rat and rabbit, nor aluminum‐induced neurofibrillary tangles in the rabbit. All these structures were demonstrated by the chicken neurofilament antisera and by silver neurofibrillary methods. IDPN‐induced axonal balloons containing accumulations of neurofilaments were equally well stained by bovine 150K and chicken neurofilament antisera. These data suggest that the 150K polypeptide of the neurofilament triplet is not a subunit of the neurofilament core and probably plays a role in axonal tr

ISSN:0092-7317    

DOI:10.1002/cne.901950409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractThe primordium of the compound eye of the mothManduca sextawas removed by surgery within 12 hours after the molt to the pupa. When the operated animals were examined as pharate adults just prior to emergence from the pupal cuticle, no eye tissue was present on the operated side. Histological examination of the brain at successive developmental stages showed that the volume of laminar neuropil on the operated side increased very little after deafferentation while the volume of the control‐side laminar neuropil increased more than 20‐fold. The impairment of development of the lamina was accompanied by a reduction in the synthesis and storage by the optic lobe of two neurotransmitter candidates, acetylcholine and 5‐hydroxytryptamine. The endogenous content of 5‐hydroxytryptamine was also reduced in these preparations. Excision of a section of the stemmatal nerve, which connects the primordium of the compound eye to the brain, also arrested the development of the lamina, but in this case the compound eye itself developed apparently normally without making contact with the brain. This finding supports the hypothesis that the centripetal growth of photoreceptor‐cell axons normally is contact‐guided. Results of neurochemical experiments on retinal tissue argue against the idea that acetylcholine, 5‐hydroxytryptamine, or gamma‐aminobutyric acid is a likely photoreceptor‐cell neurotransmitter. From these and our previous studies of the metamorphosing brain inManducawe conclude that different classes of neurons in the same central nervous system can exhibit widely different degrees of dependency on their normal innervation for their survival an

ISSN:0092-7317    

DOI:10.1002/cne.901950410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractThe projections from the claustrum to the cerebral cortex were examined in the cat by means of horseradish peroxidase (HRP) injections in various different areas of the lateral and medial surfaces of the neocortex. In all cases retrogradely labeled cells were observed in the ipsilateralclaustrum insulare(ClI). In most of the cases some labeled cells were also observed in the contralateral ClI. The number of labeled cells was higher following large HRP injections in some cortical areas, such as the motor and visual cortex, than following large HRP injections in other areas, such as the second somatic sensory cortex. The patterns of distribution of labeled cells in the ClI following the different HRP injections evidenced a prevalent anteroposterior and dorsoventral topographical arrangement. However, some degree of overlapping was evident in the distribution of cells retrogradely labeled from injections in different cortical fieldsThe results of the present study indicate that: (a) in all likelihood the claustral projections are distributed upon the entire neocortex; (b) they are not uniformly distributed upon the neocortex from the quantitative point of view; (c) the arrangement of the claustrocortical projections is predominantly but not strictly topographicalThe widespread distribution of the claustral inputs suggests that they must be integrated in different models of cortical activity.

ISSN:0092-7317    

DOI:10.1002/cne.901950411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY