摘要:

AbstractThe first‐order connections of the anterior and posterior lateral line nerves and of the eighth nerve were determined in the bowfin,Amia calva, using experimental degeneration and anterograde HRP transport techniques. The termination sites of these nerves define a dorsal lateralis cell column and a ventral octavus cell column.The anterior and posterior lateralis nerves distribute ipsilaterally to two medullary nuclei—nucleus medialis and nucleus caudalis. Nucleus medialis comprises the rostral two‐thirds of the lateralis column and contains large, Purkinje‐like cells dorsally and polygonal, granule, and fusiform cells ventrally. Nucleus caudalis is located posterior to nucleus medialis and consists of small, granule cells. Anterior lateralis fibers terminate ventrally to ventromedially in both nucleus medialis and nucleus caudalis. Posterior lateralis fibers terminate dorsally to dorsolaterally within these two nuclei. A sparse anterior lateralis input may also be present on the dendrites of one of the nuclei within the octavus cell column, nucleus magnocellularis. In contrast, the anterior and posterior rami of the eighth nerve each terminate within four medullary nuclei which comprise the octavus cell column: the anterior, magnocellular, descending, and posterior octavus nuclei. An eighth nerve projection to the medial reticular formation is also present.Some fibers of the lateralis and eighth nerves terminate within the ipsilateral eminentia granularis of the cerebellum. Lateralis fibers distribute to approximately the lateral half of this structure with posterior lateral line fibers terminating laterally and anterior lateral line fibers terminating medially. Eighth nerve fibers distribute to the medial half of the eminentia gra

ISSN:0092-7317    

DOI:10.1002/cne.901970102

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

年代:1981

数据来源: WILEY

摘要:

AbstractPhysiological experiments show that the abducens internuclear pathway is involved in the activation of only the medial rectus (MR) eye muscle. Previous anatomical experiments have shown that this pathway terminates in multiple foci within the oculomotor nucleus (OMN) of the monkey, and not only over the classical motoneuron subgroup. In this study the location of MR motoneurons in the monkey OMN is reinvestigated, and compared with the detailed pattern of terminations of the abducens internuclear pathway. The motoneurons were labelled by injections of retrograde tracer substances, HRP and [125I] wheat germ agglutinin (WGA), into extraocular muscles. Labelled MR motoneurons were found in three main divisions, called subgroup A, B, and C. Subgroup A corresponds mainly to the classical ventral MR subgroup. Subgroup B lies dorsal and caudal in OMN, occupying an area classically reserved for inferior rectus (IR). However, the representation of IR is shown to be further rostral in the dorsal OMN. Subgroup C is on the dorsomedial border of OMN. Its cells are significantly smaller than those of group A and B. In addition C could be labelled independently of the other subgroups by small injections into the outer (orbital) layer of MR muscle. This indicates a functional difference between the subgroups. It is suggested that subgroup C may be important for the tonic component of MR activity, possibly convergence. The location of abducens internuclear terminals, labelled by the injection of tritiated amino acids into the abudens nucleus, corresponds exactly to the position of MR motoneurons. These experiments provide a new picture of the internal OMN organization, and support the physiological findings that the abducens internuclear pathway activates only MR motoneurons.

ISSN:0092-7317    

DOI:10.1002/cne.901970103

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe globus pallidus (GP) of the mouse was studied by the rapid Golgi silver impregnation method. The GP was composed of large and mediumsized neurons. The large neurons had stellate cell bodies with a mean diameter of 25 μm by 28 μm and five to seven primary dendrites. The somato of the mediumsized neurons were spindle or fusiform in shape, measured 19 μm by 27 μm in average and emitted three to five primary dendrites. The large neurons were located mainly in the central part of the GP, whereas the medium‐sized neurons were observed in the peripheral part of the GP. Some GP neurons extended their dendrites into the caudatoputamen complex, sublenticular region or internal capsule. The axons of the GP neurons were seen most frequently to course medially or mediocaudally and to enter the internal capsule or fiber bundles traversing the GP; they were rarely observed to run laterally and to travel into the caudatoputamen complex. Some axons of the GP neurons were also observed to emit intra‐ or extra‐nuclear collaterals extending into the sublenticular region.Four groups of afferent fibers to the GP were observed; (1) fibers descending within the internal capsule or caudatoputamen complex to terminate or to give axon‐collaterals to the GP; (2) fibers ascending within the internal capsule or fiber bundles traversing the GP to enter the GP from its medial aspects; (3) fibers traversing the internal capsule laterally to terminate in the GP; and (4) fibers running dorsally through the sublenticular region to terminate in the GP. In addition to these four groups of afferent fibers, terminal branches were seen to arise numerously from many fibers running thr

ISSN:0092-7317    

DOI:10.1002/cne.901970104

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

年代:1981

数据来源: WILEY

摘要:

AbstractWith the aid of (H3)‐thymidine autoradiography, neurogenesis was documented in the nuclear groups of the medualla oblongata, pons, and midbrain, as well as in the brain stem reticular formation of the rabbit. Following single injections of (H3)‐thymidine, counts were taken of intensely labeled neurons within the nuclei of the functional columns related to the cranial nerves, nuclei of several other functional classifications, and nuclei that did not fit into a functional category. In the brain stem as a whole, neurogenesis was found to occur between days 10.0 and 18.5 of gestation; however, the majority of nuclei studied contained intensely labeled neurons only between days 12.0 and 15.0. Only in the pontine nucleus and the tectum were intensely labeled cells observed as late as day 18.5. Directional gradients of histogenesis were often observed within, as well as between, various nuclei. Within the nuclear columns related to the cranial nerves, a clear mediolateral spread of neurogenesis was observable such that nuclei of the motor columns reached a peak in neurogenesis before those in the sensory columns. Likewise, a mediolateral proliferation pattern was seen in the brain stem reticular formation. Other individual directional gradients were discernible; however, in the brain stem as a whole, distinct overall gradients were not observable. In many individual nuclei, gradients in neuron size were observed such that large neurons preferentially arose prior to smaller neurons. Information pertaining to gradients in neurogenesis, as well as to relationships among functionally related nuclei, are disscus

ISSN:0092-7317    

DOI:10.1002/cne.901970105

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe present paper provides an atlas showing the distribution of melanin‐containing nerve cells in the human brainstem. It was found that neuromelanin, which can be viewed as a waste product of catecholamine metabolism, is suitable as a natural marker for catecholaminergic neurons in the medulla oblongata, pons, and the mesencephalon of the adult human brain. Within these areas of the brain, there is a striking similarity between the location of melanin and the catecholamine cell bodies described in various animals and in human fetuses, whereas no melanin was found in the diencephalic dopaminergic cell groups. Cell counts from the center of each area showed that the mean density of melanin‐containing perikarya varied considerably between the different ar

ISSN:0092-7317    

DOI:10.1002/cne.901970106

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe medial (M) and posteromedial cortical (C3) amygdaloid nuclei and the nucleus of the accessory olfactory tract (NAOT) are disignated the “vomeronasal amygdala” because they are the only components of the amygdala to receive a direct projection from the accessory olfactory bulb (AOB). The efferents of M and C3 were traced after injections of3H‐proline into the amygdala in male golden hamsters. Frozen sections of the brains were processed for autoradiography.The efferents of the “vomeronasal amygdala” are largely to areas which are primary and secondary terminal areas along the vomeronasal pathway, although the efferents from C3 and M terminate in different layers in these areas than do the projections from the vomeronasal nerve or the AOB. Specifically, C3 projects ipsilaterally to the internal granule cell layer of the AOB, the cellular layer of NAOT, and layer lb of M. Additional fibers from C3 terminate in a retrocommissural component of the bed nucleus of the stria terminalis (BNST) bilaterally, and in the cellular layers of the contralateral C3. The medial nucleus projects to the cellular layer of the ipsilateral NAOT, layer lb of C3, and bilaterally to the medial component of BNST.Projections from M to non‐vomeronasal areas terminate in the medial preoptic area‐anterior hypothalamic junction, ventromedial nucleus of the hypothalamus, ventral premammillary nucleus and possibly in the ventral subiculum.These results demonstrate reciprocal connections between primary and secondary vomeronasal areas and between the secondary areas themselves. They suggest that M, but not C3, projects to areas outside this vomeronasal network. The medial amygdaloid nucleus is therefore an important link between the vomeronasal organ and areas of the brain not receiving direct vome

ISSN:0092-7317    

DOI:10.1002/cne.901970107

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe anterior cortical (C1) and posterolateral cortical (C2) nuclei of the amygdala are designated the “olfactory amygdala” because they each receive direct projections from the main olfactory bulb. The efferents of these nuclei were traced after sterotaxic placement of 1—5 μCi tritiated proline in the corticomedial amygdala of male golden hamsters. Following survival times of 12, 24, or 48 hours, 20 μm frozen sections of the brains were processed for light microscopic autoradiography.Efferents from C2 terminate in layers II and III of the olfactory tubercle and in layer lb of pars ventralis and pars medialis of the anterior olfactory nucleus. Fibers from this nucleus also project to layers I and II of the infralimbic cortex and to the molecular layer of the agranular insular cortex. More posteriorly, fibers from C2 teminate in layer I of the dorsolateral entorhinal cortex, and in the endopiriform nucleus.From C1, efferent fibers travel in the stria terminalis and terminate in the precommissural bed nucleus of the stria terminalis and in the mediobasal hypothalamus. Efferents from C1 also innervate the molecular layer of C2, the amygdalo‐hippocampal area, and the adjacent piriform cortex.Neurons in both C1 and C2 project to the molecular layer of the medial amygdaloid nucleus and the posteromedial cortical nucleus of the amygdala, the plexiform layer of the ventral subiculum, and the molecular layer of the lateral entorhin

ISSN:0092-7317    

DOI:10.1002/cne.901970108

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

年代:1981

数据来源: WILEY

摘要:

AbstractGABAergic neurons have been identified in light and electron microscopic preparations of rat retina by an immunocytochemical localization of the GABA‐synthesizing enzyme, glutamic acid decarboxylase (GAD). GAD‐positive neuronal somata are found only in the inner and middle parts of the inner nuclear layer, and GAD‐positive neuronal terminals are observed exclusively within the inner plexiform layer (IPL) and the outermost part of the ganglion cell layer. Dense aggregations of GAD‐positive terminals alternate with less dense zones to form a lamination of the IPL. GAD‐positive terminals contain pleomorphic synaptic vesicles and are thepresynapticelements of conventional synapses onto bipolar and amacrine cell processes, as well as onto the somata and dendrites of ganglion cells. In addition, GAD‐positive terminals arepostsynapticto unstained bipolar terminals and are components of synaptic dyads where they occasionally appear to form reciprocal synapses with the bipolar terminals, and serial synapses with unstained amacrine processes. Probable synaptic contacts between adjacent GAD‐positive terminals also have been observed. Most of the synapticinputto GAD‐positive terminals comes from bipolar cells, while the small remaining input mainly comes from other GAD‐positive terminals. The synapticoutputof GAD‐positive terminals is greatest to bipolar cells, followed in decreasing order by GAD‐negative amacrine cells, ganglion cells, and other GAD‐positive cells. The total synaptic output of GAD‐positive cells appears to be more than twice as great as the total input to these cells.The location of GAD‐positive somata, the distribution of GAD‐positive terminals, and the synaptic relationships formed by these terminals all indicate that amacrine cells are the only GABAergic neurons in rat retina. Our observations also indicate that not all amacrines are GABAergic and suggest that GABAergic neurons may be limited to a narrow field subclass of amacrine cell. The findings concerning the synaptic connections of GABAergic amacrines suggest that such cells are the first link in several divergent pathways from bipolar to ganglion cells and that they probably serve more than one function since they feed synaptic activity forward directly upon ganglion cells as we

ISSN:0092-7317    

DOI:10.1002/cne.901970109

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

年代:1981

数据来源: WILEY

摘要:

AbstractThis paper concerns the banding pattern produced in the inner plexiform layer of rat retina by glutamic acid decarboxylase (GAD) immunocytochemistry. It presents a comparison of this pattern with the dendritic stratification of neurons that are reasonable candidates for GABAergic amacrine cells in Golgi preparations, and also with the banding patterns produced by other histochemical techniques. First, the spacing of five dense GAD‐positive bands and four intervening less dense bands in central retina is quantitatively described. Second, examples of a particular, morphologically homogenous group of Golgi‐impregnated amacrine cells are examined in the details of their structure, espeically with regard to their dendritic stratification. Computer reconstructions of the dendritic trees of some of these narrow‐field, multistratified amacrines are compared with the GAD‐positive banding pattern. This group of amacrines is judged to represent many of the GABAergic neurons in rat retina, accounting for the form and distribution of GAD‐positive synaptic terminals by their dendritic morphology and stratification. Third, a general schema for the laminar subdivision (stratification) of the inner plexiform layer in rat retina is derived from a comparison of the results of several histochemical procedures. Finally, similarities and differences in the distribution of GAD‐positive amacrine cell dendrites are noted among mammals and the functional implications of their broad distribution are discussed. A conspicuous difference is cited between mammals and certain nonmammalian vertebrates in which GAD‐positive dendrites are restricted to sublaminab(ON‐center cells) of the inner

ISSN:0092-7317    

DOI:10.1002/cne.901970110

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe morphology of the cochlear nuclei of normal and reeler mutant mice were studied in Nissl‐stained sections. The cochlear nucleus in both mice is divisible into three parts: the anteroventral, posteroventral, and dorsal nuclei. Nine cell types can be recognized in the normal mouse. In the anteroventral nucleus spherical cells occupy the rostral pole. Globular cells are located caudally and extend to the interstitial region of the anteroventral nucleus. In the posteroventral nucleus multipolar cells are located rostrally and dark‐staining cells occupy the caudal pole. Multipolar cells are also present in the anteroventral nucleus and in the deep region and molecular layer of the dorsal cochlear nucleus. The dorsal and lateral aspects of the ventral nuclei are covered by a granule cell layer. The dorsal nucleus consists of superficial molecular and pyramidal layers and a deep region. The deep region contains small and giant cells as well as multipolar cells. The pyramidal layer is made up of pyramidal cells, horizontal cells, and granule cells. Small cells are also present in the molecular layer and throughout the ventral nuclei.The dorsal cochlear nucleus of the reeler mutant mouse is disorganized and the molecular layer is reduced in thickness. The organization of the pyramidal layer is disrupted with granule cells superficial to pyramidal and horizontal cells. Cells which appear to be homologous to pyramidal cells are also present in the deep region of the dorsal nucleus. The total number of granule cells is reduced by an average of 42% over the whole nucleus and the reduction in granule cells is greatest in the granule cell cap covering the dorsal and lateral surface of the ventral cochlear nuclei. The cytoarchitecture of the ventral cochlear nucleus appears nor

ISSN:0092-7317    

DOI:10.1002/cne.901970111

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

年代:1981

数据来源: WILEY