摘要:

AbstractThe cytoarchitecture of the pretectal complex of the squirrel monkey was examined in Nissl‐ and myelin‐stained sections in the coronal, horizontal, and sagittal plane. Five different pretectal subdivisions can be identified on the basis of their nuclear morphology. The general location and cytoarchitecture of these pretectal nuclei are similar to those described for non‐primate mammals. Thus, the nomenclature used to designate the pretectal nuclei in other species can now be applied to the squirrel monkey. According to this standard terminology, the pretectal complex of the squirrel monkey consists of the nucleus of the optic tract; the pretectal olivary nucleus; and the medial, anterior, and posterior pretectal nuclei. The pattern of retinal innervation to the pretectum was also determined by placing intraocular injections of3H‐proline into one eye and processing the tissue according to standard autoradiographic techniques. The pattern of transported label is more dense over the contralateral nuclei than over the ipsilateral nuclei. In particular, dense transported label is observed bilaterally over the pretectal olivary nucleus and the nucleus of the optic tract with sparse label over the posterior and medial pretectal

ISSN:0092-7317    

DOI:10.1002/cne.902320402

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe spatial interrelationship of neurons in area 7a in the inferior parietal lobule that project through the corpus callosum to the corresponding field in the contralateral hemisphere or to the ipsilateral prefrontal cortex has been analyzed in macaque monkeys by using double‐labeling procedures with retrogradely transported fluorescent dyes. The populations of callosal and associational projecting neurons have similar laminar distributions and are topographically intermingled. Less than 1% of the neurons were double‐labeled, thus suggesting that the two populations are largely separate. Two‐dimensional reconstructions of the distribution of labeled cells made on flattened reconstructions of the inferior parietal lobule revealed that the areal distribution of the two cortico‐cortical output arrays is complex. Although each pattern of labeling showed some discontinuities in density, there was no obvious periodicity within or between the spatial distributions of the two projecting populations. It was consistently observed that the cortex of the lateral wall of the intraparietal sulcus, adjacent to area 7a, projects more heavily to the prefrontal cortex than does area 7a

ISSN:0092-7317    

DOI:10.1002/cne.902320403

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

年代:1985

数据来源: WILEY

摘要:

AbstractLumbar dorsal roots of adult frogs were crushed or cut and reanastomosed. Following survival times of up to 75 days, the regenerating dorsal roots were recut and anterogradely injury‐filled with horseradish peroxidase. This revealed that in the adult frog, regenerating axons re‐enter the spinal cord. Comparison of the distribution of these axons with that of normal, dorsal root axons showed that there is a partial restoration of the segmental distribution in the gray matter. However, the long ascending sensory tract of the dorsal funiculus was not restored, The dorsal funiculus was markedly gliotic and had relatively few labelled, regenerated axons. The labelled axons that were seen in the dorsal funiculus either extended longitudinally for a distance just beneath the pia, apparently in association with the glia limitans, or traversed the region to enter the dorsal gray matter. Most of the large and small diameter axons that entered the gray matter did so by passing through the region of the dorsolateral fasciculus. Within the gray matter, small diameter, regenerated axons arborized in the region of the dorsal terminal field, a region that has been shown in the normal frog to receive cutaneous afferents only. Many large diameter axons, presumably muscle afferents, arborized in the ventral terminal field, a region shown in the normal frog to receive muscle afferents exclusively. However, many of these large diameter axons had arborizations that extended to both terminal fields, thus suggesting that some abberant connections are made during dorsal root regeneration in the adult f

ISSN:0092-7317    

DOI:10.1002/cne.902320404

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

年代:1985

数据来源: WILEY

摘要:

AbstractBoth the polarity of the axonal growth and the formation of the optic fiber pattern early in retinal morphogenesis were studied in silver stained whole mounts of embryonic chick, quail, and pigeon retinae. The surface area of the retina and of the optic fiber layer increases in size exponentially, the optic fiber layer expanding faster than the retina. The optic fiber layer covers the retinal surface at E5 in quail and at E6 in chick and pigeon. In all species studied, the retinal fiber layer does not expand homogeneously with the optic nerve head as the center. Instead, the retinal fiber layer enlarges with polarities in the dorsal to ventral and nasal to temporal direction. The very first axon bearing ganglion cells appear at stage 16 in the dorsal and central portion of the retina and grow ventrally to merge at the optic disk. From stage 23 on, the optic fiber layer expands faster in the temporal than in the nasal side. Measurements on the initial polarization of young axonal processes show that the axonal growth is directed toward the optic fissure and the optic nerve head. This growth polarization is found at the onset of growth cone formation and in axons far from the nearest ganglion cells or ganglion cell axons. Therefore axon‐axon interaction cannot be involved in the initial axon orientation early in retinal morphogenesi

ISSN:0092-7317    

DOI:10.1002/cne.902320405

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe immunohistochemical localization of neuronal cell bodies and axons reactive for substance P (SP) and methionine‐enkephalin (ME) was investigated in the corpus striatum of the adult cat brain and compared with that of glutamate decarboxylase (GAD), synthetic enzyme for γ‐aminobutyric acid. Striatal cell bodies reactive for ME could be identified only in colchicine treated cats, are medium size, ovoid striatal cells, and are found in large numbers in a more or less even distribution throughout the caudate nucleus, putamen, and nucleus accumbens. The striatial region most densely occupied by ME‐immunoreactive cells is the ventral and central part of the caudate head. Modest numbers of larger ME‐reactive neurons are dispersed throughout the entopeduncular nucleus and the pars reticulata of the sub‐stantia nigra. Striatal cells of medium size reactive for SP could be identified, with or without colchicine, in largest numbers in the medial half of the caudal three‐fourths of the putamen and in clusters of irregular size and shape in the head of the caudate nucleus. Cells reactive for SP are also common in layer II and the islands of Calleja of the olfactory tubercle. We could not reliably visualize GAD‐positive cell bodies in the striatum, even with colchicine treatment; however, they could be seen readily in all pallidal structures such as the globus pallidus, ventral pallidum, entopeduncular nucleus, and substantia nigra.Axons reactive for ME are found mainly in the globus pallidus where they form a dense and even network throughout the nucleus. The globus pallidus is almost devoid of SP reactivity except near its extreme caudal pole. Conversely, SP‐immunoreactive axons form dense meshworks in the entopeduncular nucleus and substantia nigra where ME immunoreactivity is minimal. Fewer, but still ample numbers, of SP‐reactive axons are present also in the ventral tegmental and retrorubral areas of the midbrain tegmentum and in the ventral pallidum of the basal forebrain, but only sparse ME‐reactive axons are present in these areas. This differential distribution of SP‐ and ME‐containing axons in the pallidal and nigral structures stands in contrast to the relatively homogeneous and dense distribution of GAD‐containing axons throughout the dorsal and ventral pallidum, entopeduncular nucleus, and substantia nigra. These data suggest that (1) the striatum can be dissected into component parts on the basis of the histochemical properties of its cells, (2) the output structures of the corpus striatum (entopeduncular nucleus, substantia nigra, ventral pallidum) are more influenced by SP than ME mechanisms, (3) the globus pallidus, which is involved primarily with an intrinsic corpus striatal circuit through the subthalamic nucleus, is more influenced by ME than SP mechanisms, and (4) the ventral pallidum is cornparable to the entopeduncular nucleus and nigra in that it receives manyy SP‐ and GAD but apparently on

ISSN:0092-7317    

DOI:10.1002/cne.902320406

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

年代:1985

数据来源: WILEY

摘要:

AbstractSome corticospinal neurons give rise to axons which terminate directly upon motoneurons, thereby establishing corticomotoneuronal connections. The location of corticomotoneuronal synapses upon motoneurons innervating intrinsic muscles of the hand in the monkey was demonstrated by the use of intra‐axonal and intracellular horseradish peroxidase (HRP). After a number of corticospinal axons originating from the “hand” area of the precentral gyrus had been injected with HRP in the lateral funiculus at C7‐C8, a number of nearby identified intrinsic hand muscle motoneurons were also injected. Connections between corticomotoneuronal fibres and motoneurons were reconstructed from longitudinal parasagittal sections treated by the cobalt‐enhanced diaminobenzidine method.Corticospinal axons in the lateral funiculus gave rise to main collaterals which provided an extensive arborization in lamina IX, where it was predominantly longitudinal, and in the adjacent intermediate zone.En passantand single or clustered groups of terminal boutons arose from preterminal branches of these arbors. Seven light‐microscopically identified corticomotoneuronal synapses were found. They were located upon the dendrites of recipient motoneurons at 40 μm to 750 μm from the soma and ranged in size from 0.6 × 3.0 μm to 2.4 × 3.6 μm.The results suggest that each main collateral of a corticomotoneuronal axon establishes very few synaptic contacts, and possibly only one, with the dendrites of recipient motoneurons. This small number of contacts per motoneuron is consistent with the small amplitudes of minimal and unitary corticomotoneuronal EPSPs recorded from forelimb and

ISSN:0092-7317    

DOI:10.1002/cne.902320407

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe present report provides evidence to challenge the traditional view that cerebellar Golgi cells are derived from the ventricular neuroepithelium, postulating instead that they originate from external granule cells. Supporting evidence for this assertion comes from three sources: (1) Typical Golgi cells are found in ectopic granule cell colonies, both outside the cerebellum (in the subarachnoid space) and also within the cerebellar cortex between fused folia. Because ectopic granule cell colonies are derived from external granule cells, which become displaced after treatment with 6‐hydroxydopamine (6‐OHDA), it was assumed that the ectopic Golgi cells also stem from such displaced external granule cells. (2) In order to demonstrate that Golgi cell precursors migrate from the external granular layer into the Purkinje cell plate, the development of the cerebellar cortex was studied over the period of Golgi cell genesis. On E19 the external granular layer in the rat is subdivided into an outer proliferative and an inner subproliferative zone. At the inner margin of the external granular layer, and in the marginal zone, radially oriented, darkly staining cells are present that exhibit all the characteristics of migrating neurons possessing a leading process oriented toward the Purkinje cell plate, a somatic cilium, and a close association with radial glia fibers. In later stages, these cells are also found deep to the Purkinje cell plate. Because Golgi cells arise during the period between E19 and postnatal day 2 in the rat (Altman and Bayer, 1977, 1978) and as the basket cells, the first neurons of proven origin from the external granular layer, are not produced before the second postnatal day (Altman, 1972), the earlier migrating neurons are presumed to be Golgi cells. (3) Available data from cell kinetic3H‐thymidine studies show that there is no unequivocal evidence for Golgi cell genesis from the ventricular neuroepithelium, because, at the time of Golgi cell birth, ventricular and external granular stem cell populations are proliferating, and with the present methods it is not possible to decide which of these are the precursors of Golgi cells. Thus, taken together, the findings of this study show that Golgi cells are more likely to arise from the external granular layer than from the ventricular neuroepithelium. This concept would unify cerebellar histogenesis by proposing that projection neurons arise from the ventricular neuroepithelium, whereas all interneurons of the cerebellar cortex are descendants of the external granular

ISSN:0092-7317    

DOI:10.1002/cne.902320408

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe cells in the dorsal column nuclei, lumbosacral spinal cord, lateral cervical nucleus, and nucleus z that project to the medial accessory portion of the inferior olive of cats were identified with retrograde tracing techniques. Injections of wheat germ agglutinin complexed to horseradish peroxidase were made in the caudal portion of the medial accessory olive, either (1) involving no portion of the dorsal accessory olive or (2) involving in addition the caudal tip of the dorsal accessory olive. The tissue was processed with tetramethyl benzidine. The locations of all relay neurons were compared with those of dorsal accessory olive projection neurons, as described in a previous study (Molinari, 1984a).Localized populations of neurons gave rise to most of the projection to the medial accessory olive. These neurons were found in the peripheral portions of the dorsal column nuclei caudal to the obex and in the ventromedial ventral horn of the entire lumbosacral enlargement. Few projection neurons were found in the lateral cervical nucleus and none in the nucleus z.Neurons in the peripheral dorsal column nuclei and ventromedial ventral horn were labeled by injections in either the medial or dorsal accessory olives. Following medial accessory olive injections, however, they constituted the only labeled somatosensory neurons, while following dorsal accessory olive injections they represented only a small fraction of the labeled neurons. Based on their locations, it is proposed that these neurons might be the source for both the medial and dorsal accessory olives of information signalling movement of the proximal limb. Such a proposal is consistent with functional descriptions of the medial and dorsal accessory olives and the cerebellar anterior lobe.

ISSN:0092-7317    

DOI:10.1002/cne.902320409

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

年代:1985

数据来源: WILEY

摘要:

AbstractBy means of preembedding immunohistochemistry, two types of gonadotropin‐releasing hormone (GnRH) positive neurons in the rat could be identified and characterized in the preoptic region and in the diagonal band: (1) a “smooth” GnRH neuron with relatively even cytoplasmic contours, and (2) a “spiny” GnRH neuron with thorn‐like protrusions of the perikaryon and cell processes. Both cell types contain the same organelles in similar number and distribution, but they differ in the number of synaptic contacts. In general, GnRH cell bodies have a large round or ovoid nucleus, well‐developed rough endoplasmic reticulum arranged in multilayered stacks or as individual cisternae, and several Golgi complexes. Lysosomes are not numerous under the conditions studied. Specializations include kinocilia, nematosomes, and lamellar whorls. Throughout the cytoplasm, scattered dense core vesicles with a diameter of 100 nm and clear vesicles with a diameter of 30–40 nm can be seen with a preferential localization close to the cell membrane. The cell processes of smooth GnRH cells close to the perikaryon appear as extensions of the perikaryal cytoplasm with all organelles except the nucleus. The two neurites originate from the perikaryon as tapering cones over a distance of 200–300 μm, until they reach a diameter of 0.5–3 μm. Cell processes of spiny GnRH cells show bifurcations, protrusions, or invaginations and contain clear and dense core vesicles in their spines. In areas distant from the perikaryon, immunoreactive fibers with a large number of dense core and clear vesicles can occasionally be seen to terminate synaptically or asynaptically on other neurons. The GnRH neurons show postsynaptic specializations at the level of the perikaryon and at cell processes, when apposed by a presynaptic terminal. Such synaptic contacts are seen less frequently on smooth cells than on spiny cells. Large areas of the GnRH cell may be covered by a thin glial lamella, which separates the cell body from the surrounding neuropil. The results indicate the existence of two populations of GnRH cell bodies with different patterns of innervation, which suggest different i

ISSN:0092-7317    

DOI:10.1002/cne.902320410

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

年代:1985

数据来源: WILEY

摘要:

AbstractCentral distribution of efferent and afferent components of the pudendal nerve was studied by the horseradish peroxidase (HRP) method in 13 macaque monkeys, i.e., in nine Japanese monkeys (Macaca fuscata), two rhesus monkeys (Macaca mulatta), and two crab‐eating monkeys (Macaca fascicularis). The enzyme was applied to the central cut end of the pudendal nerve; then the monkeys were allowed to survive for 36 to 72 hr.Retrogradely labeled neuronal cell bodies of pudendal motoneurons constituted a slender longitudinal cell column in the ventral horn. The cell column extended from high or middle S1 to high or middle S2 in eight monkeys, from middle or low L7 to high S2 in four monkeys, and from high L7 to middle S1 in a monkey. The cell column appeared to correspond to Onuf's X nucleus in man. No sex difference was recognized in the position of the cell column.The average number of HRP‐labeled pudendal motoneurons was larger in male than in female adult Japanese monkeys, whereas no sex difference was found in the average soma diameter of the pudendal motoneurons.Transganglionically labeled axons entered into the spinal cord through the S1 and S2 dorsal roots in 12 monkeys and through the L7 and S1 dorsal roots in one monkey. Labeled axons were distributed ipsilaterally in laminae I–VI and X of the spinal cord at the same and adjacent levels of entry of HRP‐labeled dorsal root fibers (from L7 to S3 in 12 monkeys and from L6 to S3 in one monkey). At the levels of entry, some of the labeled dorsal root fibers crossed the midline of the cord through the dorsal commissural gray to distribute contralaterally in the medial portions of lamine I–VI, especially laminae III–V, of the dorsal horn. Although the craniocaudal extent of HRP‐labeled afferent fibers varied somewhat among 13 monkeys examined, no HRP‐labeled axons were observed in the gray matter of the spinal cord segments cranial to L6 and caudal to S3. In a Japanese monkey with a postoperative survival time of 72 hr, two clusters of labeled axons were observed ipsilaterally in the medial portions of the

ISSN:0092-7317    

DOI:10.1002/cne.902320411

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

年代:1985

数据来源: WILEY