摘要:

AbstractThe cortico‐geniculate pathways of normally‐pigmented and Siamese cats have been studied by autoradiography following injections of3H proline into cortical area 17. Normal Siamese cats and Siamese cats that were raised with one eye sutured or removed have been compared with normally‐pigmented cats treated in the same manner. The cortico‐geniculate projection from area 17 passes to all parts of the lateral geniculate nucleus in normal cats and distributes to all geniculate layers (Updyke, '76). This distribution was essentially unaffected by an early monocular suture or enucleation. In Siamese cats, the cortico‐geniculate projection to lamina A and to the lateral normal segment of lamina A1 was normal, but little or no label was seen in the abnormal segment of lamina A1. The interlaminar zones adjacent to the abnormal segment of lamina A1 were densely filled with label, as though the cortico‐geniculate axons avoid this segment. Unilateral enucleation or lid‐suture did not affect this distribution, suggesting that it does not depend upon visual experience. These Siamese cats were all identified by electrophysiological studies as having a normal topography of the geniculo‐cortical pathways. That is, they were

ISSN:0092-7317    

DOI:10.1002/cne.901790102

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe present study documents that in the stingrayDasyatis sabinathe numbers of (1) dorsal root ganglion cells, (2) dorsal root axons, (3) ventral root axons and (4) “motor” cells in the ventral horn increase steadily as the animals increase in size. This increase in axonal and neuronal numbers persists much further into adult life than is the case for other vertebrates that have been studied from this point of view. We hypothesize this steady increase in axonal numbers may be related to the ability of fish to regenerate parts of their central and/or peripheral nervous syst

ISSN:0092-7317    

DOI:10.1002/cne.901790103

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

年代:1978

数据来源: WILEY

摘要:

AbstractPrenatal cerebellar development was investigated with three approaches. In normal embryos sectioned in three planes morphological and cytological changes were determined at daily intervals beginning on embryonic day 13 (E13). A similar series of X‐irradiated embryos was used to study changes in neuroepithelial organization and in the location of primitive (radiosensitive) or differentiated cells. Finally, to quantify the time of origin of different classes of cerebellar neurons with the progressively delayed labelling procedure, we used autoradiograms from adult rats whose mothers were injected with two successive daily doses of3H‐thymidine on overlapping days from day E13 on.The cerebellar anlage was delineated in the dorsal metencephalon by the collapse of its ventricular lining after X‐irradiation. This “collapsing neuroepithelium” was located laterally on day E13, then it spread medially and reached the midline on day E16. Deep nuclear neurons began to differentiate on day E13, with two‐thirds forming on day E14; Purkinje cell formation peaked on day E15, with a few cells still forming on day E16. It was postulated that the deep nuclear neurons settled first in the superficial “nuclear zone,” and that the Purkinje cells gathered temporarily in the underlying “transitory zone,” adjacent to the collapsing neuroepithelium.In the next period of cerebellar development four major events were recognized. (1) Beginning on day E17 the cells of the nuclear and transitory zones became intermingled. It was postulated that the Purkinje cells were migrating radially through the ranks of the stationary deep nuclear neurons and assembled under the spreading canopy of a fibrous plexus and the external germinal layer. (2) It was also on day E17 that the external germinal layer began to form as one of the prongs of the “germinal trigone” in the posteroventral aspect of the cerebellum. On the succeeding days the external germinal layer spread over the surface of the cerebellum; in the vermis in a rostral direction. (3) Two cell types destined to settle in the future granular layer, the pale cells and the Golgi cells, began to form at a relatively slow rate on day E19. Chronological considerations suggested that they were generated in the regressing, noncollapsing neuroepithelium of the cerebellar ventricle. (4) From the beginning (day E17) of its genesis posteroventrally, the primitive cerebellar cortex bridged the midline. As the fused cortex spread rostrally, the vertical ventricular cleft separating the underlying portions of the cerebellum became shallower and then disappeared; the process was completed in the anterior cerebellum by day E22. By the time of birth the maturation of the neurons of the deep nuclei appeared advanced but the maturation of the prenatally produced neurons of the cortex does not start until after birth when a new class of neurons is generated in the

ISSN:0092-7317    

DOI:10.1002/cne.901790104

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

年代:1978

数据来源: WILEY

摘要:

AbstractAspects of the prenatal development of the inferior olive, lateral reticular nucleus, nucleus reticularis tegmenti pontis, and of the pontine gray were investigated in the rat. The material used was the same as in the preceding study of cerebellar development, including histological preparations from normal and x‐irradiated embryos at daily intervals (days E13 to E22), and autoradiograms from adult rats injected with two successive doses of3H‐thymidine on overlapping days from days E13 + 14 on.Neurons of the inferior olive form on days E13 and 14: those settling rostrally in the principal nucleus somewhat ahead of those settling in the medial accessory nucleus caudally. The olivary neurons are generated in the neuroepithelium of the lateral recess of the fourth ventricle, migrate ventrally by way of the olivary migratory stream, split into two branches and provide cells to the olivary complex from its lateral and medial aspect. The migrating cells are differentiated, radioresistant elements. It was postulated that since the olivary migratory path and the course of olivary fibers (the inferior cerebellar peduncle) are on the same trajectory, climbing fibers could reach the surface of the cerebellum before the arrival of the radially migrating Purkinje cells.Neurons of the lateral reticular nucleus form predominantly on days E13 and 14, of the nucleus reticularis tegmenti pontis on days E15–17, and of the pontine gray on days E17–19. The pontine neurons originate several days after but at the same site as the olivary neurons. The cells migrating in the pontine migratory stream are undifferentiated elements and follow a course different to that of their prospective axons in the middle cerebellar peduncle. The earliest forming pontine neurons settle near the pyramidal tract, the later arriving cells form cap‐like shells around this core. Axonogenesis of pontine cells begins after the settling of the perikarya on day E19. The middle cerebellar peduncle appeared to approach the cerebellum on day E22, suggesting that pontine mossy fibers do not establish contact with cerebellar elements before the perinatal period, by which time the external germinal layer and the Purkinje cells have formed a cortical mantle over the entire cerebellum.In an attempt to correlate the chronology of cytogenesis in some of the precerebellar nuclei with cell production and maturation in the cerebellum, it was hypothesized that mossy fibers of reticular origin exert influence on Purkinje cell dendrites in the lower parts of the molecular layer, whereas mossy fibers of pontine origin influence the upper parts of Purkinje cell dendrites. Reference is made to behavioral results indicating the mediation of dissociable functions by elements of the lower and upper molecu

ISSN:0092-7317    

DOI:10.1002/cne.901790105

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe cortico‐pontine projections from striate (kV), parastriate (paV) and peristriate (peV) areas of the neocortex of the cat have been investigated using an anterograde axoplasmic tracing method. Injections of tritiated amino‐acids have been made at cortical locations whose visual field positions were determined in some experiments electrophysiologically. It has been found that the density of the projection varies depending on the location of the injections within each area. In addition differences in the density of the pontine projection have been found between the three visual areas. Both in kV and paV no pontine projection was detected from cortex representing the area centralis. An increase of the projection from cortex with paracentral to peripheral visual field representations was found in kV for the lower hemifield (the upper hemifield has not been investigated) and in paV for the entire hemifield. In addition it has been found that a denser projection arises from the representation of the lower visual field in paV and peV than from the representation of the lower visual field in paV and peV than from the representation of the upper visual field.The cortico‐pontine projection has been found to increase from kV (V1) through paV (V2) to peV. Since the injections in peV were not restricted to the region of the third visual representation (V3), they do not allow a definite conclusion to what extent the increased projection from peV can be attributed to V3.The terminations from the three visual areas are largely restricted to the rostral third of the pontine basilar gray. The labelled terminals were not restricted to any one of the nuclei of this region which have been delimited by Brodal and Jansen ('46). The terminals formed patches of variable size near the ventral aspect of the cerebral peduncles. A clear retinotopic distribution of these patches could not be demonst

ISSN:0092-7317    

DOI:10.1002/cne.901790106

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe nerve cells of the gelatinosal complex (laminae II and III) were examined in various planes of section in Golgi and Nissl preparations of the lumbosacral spinal cord of the adult monkey. An attempt was made to characterize the neurons based on morphological variations and establish criteria for consolidation or separation of laminae II and III. In Nissl preparations the laminae essentially conform to Rexed's ('52) description for the cat. In Golgi preparations impregnated neurons of the gelatinosal complex show a spectrum of morphological variation. These variations, however, are not restricted by Rexed's border between laminae II and III. In either lamina the cells vary in size from small (12 µm × 8 µm) to medium (30 µm × 25 µm) and in shape from fusiform to polygonal. Polygonal neurons are prevalent in the dorsal part of lamina II (Rexed's outer zone) and some have craggy contours.Axons of the cells of the gelatinosal complex vary in diameter, but most measure around 1.0 µm with some up to 2.0 µm. Their course is often a meandering one which cannot be followed. Those from cells in the outer zone of lamina II are different. They issue collaterals to lamina I then immediately enter the overlying white matter. Golgi type II (short axoned) cells were not definitively demonstrated. Nonetheless, the neurons of the gelationosal complex display stalked dendritic appendages and axon‐like processes which are similar to those described on Golgi type II interneurons elsewhere in the central nervous system. For this reason, in spite of the long axons and relatively large dimensions of the neurons of the gelationosal complex, their circuitry is suspected to be similar to that of local circuit interneurons.The dendritic arbor of the cells of the gelatinosal complex, as viewed in horizontal sections, generally extends longitudinally with little mediolateral spread. In sagittal sections a stratified pattern of dendritic arborization divides the gelatinosal complex into three regions: (1) an outer region which corresponds to Rexed's ('52) outer zone of lamina II, (2) a middle region composed of the remainder of lamina II and the dorsal portion of lamina III, and (3) an inner region or ventral part of lamina III. A large portion of the dendritic arbors of cells in the outer region spread ventrally at oblique angles while those from the inner region spread dorsally. Dendrites arising from cells in the middle region, on the other hand, extend almost exclusively in the longitudinal plane, are often of considerable lengths, and give rise to unique recurrent branches. The dendritic arborization is discussed in relation to the primary afferents to the gelatinosa

ISSN:0092-7317    

DOI:10.1002/cne.901790107

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

年代:1978

数据来源: WILEY

摘要:

AbstractThis study was undertaken to examine the relation between the possession of the so‐called pit organs, which are sensitive infrared receptors innervated by the trigeminal nerve, and the sensory trigeminal nuclei. The sensory trigeminal system of Python reticulatus was investigated by means of myelin and Nissl staining techniques.It appears from the study that the sensory trigeminal system consists of two separate components. One of these resembles the sensory trigeminal system, known of other vertebrates, and is referred to as the common sensory trigeminal system. It comprises a short ascending part to the principal sensory trigeminal nucleus and a longer descending part to the nucleus of the descending trigeminal tract and upper cervical segments. The subdivision of the trigeminal system, as proposed by Olszewski ('50) for mammals, could be applied to the common sensory trigeminal system of the python.The second component is situated laterally to the common descending system. It is composed of descending fibres which terminate in a huge, separate nucleus. This is called the nucleus of the lateral descending trigeminal tract. This component was initially recognized in snakes possessing infrared receptors, but seems not to be restricted to these animal

ISSN:0092-7317    

DOI:10.1002/cne.901790108

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe central projections of the sensory roots of the trigeminal nerve in Python reticulatus have been studied by means of the Fink Heimer technique following transsection of these roots between the trigeminal ganglia and the brainstem.The sensory trigeminal fibres are distributed to the two separate sensory trigeminal systems, described before, i.e., the common sensory and the lateral descending trigeminal system. The projections of the three peripheral trigeminal branches are restricted to their own territories of the various tracts and nuclei. Generally, the ophthalmic root projects most ventrally; the mandibular root most dorsally and the maxillary root intermediately. The ophthalmic branch descends until the level of the first cervical nerve root, the maxillary and mandibular branches proceed beyond the second cervical nerve roots.The distribution pattern of the sensory trigeminal fibres differs in two major aspects from that of other vertebrates. The first difference is a large overlap of the projection areas from the mandibular and maxillary roots. The probable occurrence of this overlap within other, mammalian, species is discussed. The second major difference is the projection into the lateral descending trigeminal nucleus. The morphology of the degenerating fibres and “boutons terminaux” in this lateral descending system is markedly different from that within the common sensory system.Preliminary notes are presented to show that the common sensory and the lateral descending systems project to different areas in the mesencephalon and diencephalon. It will also be shown that the nucleus of the lateral descending trigeminal tract is exclusively concerned in processing the infrared information relayed by the pit organs.The possibility of the presence of a separate trigeminal system in other vertebrates, equivalent to the lateral descending trigeminal system of the python, is discus

ISSN:0092-7317    

DOI:10.1002/cne.901790109

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

年代:1978

数据来源: WILEY

摘要:

AbstractIn the present study, surgically removed adult human sympathetic ganglia were explored for the presence of small intensely fluorescent (SIF) cells using a combined monoamine fluorescence and electron microscopic method (Chiba et al., '76b). It was confirmed that SIF or granule‐containing (GC) cells exist as a persisting constituent of the ganglia. The population of SIF cells in human sympathetic ganglia was found to be much smaller than that of the rat and the guinea pig. Most SIF cells were found as small clusters in the connective tissue stroma in close relationship with blood vessels. GC cells were characterized by large polymorphic granular vesicles (100–300 nm in diameter) in their cytoplasm. Most GC cells were innervated by cholinergic axons which most probably originated from preganglionic sympathetic neurons. No efferent synapses were found from GC cells as far as they were examined.Axon varicosities containing small dense granular vesicles (50 nm in diameter) may correspond to varicose fluorescent network of axons among principal ganglionic neurons. The functional significance of SIF or GC cells in human sympathetic ganglia was discussed in the light of the present observati

ISSN:0092-7317    

DOI:10.1002/cne.901790110

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

年代:1978

数据来源: WILEY

摘要:

AbstractBrainstem neurons which project to lumbar, thoracic and cervical spinal levels have been identified in the North American opossum by the horseradish peroxidase (HRP) technique. Neurons which relay to all of the levels studied are located within the medullary and pontine reticular formation as well as within the nucleus cuneatus, the nucleus of the tractus solitarius, the lateral reticular nucleus, the medullary and caudal pontine raphe nuclei, the lateral, medial and inferior vestibular nuclei, the nucleus “F,” the nucleus coeruleus, and the nucleus coeruleus, para α, the red nucleus, and the interstitial nucleus of Cajal. The lateral vestibulospinal and rubrospinal systems are topographically organized, although neurons projecting to different cord levels show considerable intermingling. Our material also provides evidence that raphe‐spinal and reticulospinal connections are organized to some degree. Neurons which backfill after cervical and thoracic placements, but not after lumbar injections, are distributed within the caudal spinal trigeminal nucleus, the nucleus intercalatus, the dorsal vagal nucleus, the cuneiform area of Castaldi, the fields of Forel, and the nucleus of Darkschewitsch. Reactive neurons are present within the lateral, dorsal and posterior hypothalamic areas as well as within the periventricular and paraventricular nuclei after thoracic placements and within the superior colliculus after injections within the cervical cord. Additionally, neurons are reactive in the nucleus ambiguus, the interpolar division of the spinal trigeminal nucleus and the rostral division of the oculomotor nucleus (Oswaldo‐Cruz and Rocha‐Miranda, '68) after HRP placements into the third and fourth cervica

ISSN:0092-7317    

DOI:10.1002/cne.901790111

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

年代:1978

数据来源: WILEY