摘要:

AbstractThe present study uses selective surgical ablations combined with electron microscopic analyses to determine the number of axons in yarious catagories in rat hypogastric, pelvic, and pudendal nerves, these being the nerves to the pelvic viscera in this animal. Unmyelinated fibers predominate in all of these nerves. One of the most significant findings is that the pelvic nerve contains almost as many postganglionic sympathetic fibers as the hypogastric nerve. Previous investigators thought that the pelvic nerve supplied the parasympathetic inflow and the hypogastric nerve the sympathetic inflow to the pelvic viscera. The finding that there is a sizable sympathetic component in the pelvic nerve negates this idea, at least for the rat, and presumably calls for a reevaluation of the syndromes that arise from pelvic as opposed to hypogastric nerve section. Other findings of interest are (1) that there are unmyelinated efferent axons in the pudendal nerve, indicating that the pudendal is not a typical somatic nerve, (2) that the hypogastric nerve has a very small sensory component, and (3) that there are fibers surviving in the distal stumps of all these nerves, particularly the pelvic and hypogastric nerves.

ISSN:0092-7317    

DOI:10.1002/cne.902110102

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe ending of Reissner's fiber (RF) and structural features associated with gaps or fissures in the rostral part of the filum were investigated using light, scanning, and transmission microscopic techniques in young and mature possums of both sexes. To the best of the author's knowledge the report contains results of the first successful application of the SEM for a study of RF in the spinal cord. Some new observations suggest that while the bulk of RF is formed by the subcommissural organ and moved caudally, additional secretory products may be added by ependymal cells in the sacral and possibly other regions of the spinal cord. Evidence is provided in support of the view that RF may pass through gaps in the ependymal lining in the rostral part of the dorsal wall of the filum terminale and caudal end of the sacral cord to reach the periependymal loose tissue and possibly the subarachnoid space.The region of the gap shows the surface of the ependyma facing the lumen of the filum to be covered with microvilli and cilia, and to be in direct continuity with the external surface of the ependyma covered with basement membrane with glial processes and collagen fibers in close proximity. The present results confirm and extend observations reported by Wislocki et al. ('56).

ISSN:0092-7317    

DOI:10.1002/cne.902110103

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe organization of monoamine (MA)‐containing neuronal systems in the brain of the salamander(Necturus maculosus)was studied by means of paraformaldehyde and glyoxylic acid histofluorescence methods. The MA neurons were further characterized morphologically andhistochemically in material prepared for the demonstration of cholinesterase activity.In the brain ofNecturus, the most caudally located catecholamine (CA)‐containing cells occur in the nucleus of the solitary tract. A large population of serotonin (5‐HT)‐containing cells is also found along the entire rostrocaudal extent of the raphe region of the brainstem. At isthmal levels, a few scattered CA cells lie dorsolaterally in the so‐called acousticolateral area. These neurons can be seen to send axonal projections to the spinal cord and the cerebellum, but not to the telencephalon, and thus can not be considered as fully homologous to the locus coeruleus of reptiles, birds, and mammals. Within the midbrain, some cells displaying a strong CA fluorescence and staining intensely for cholinesterases are present near the oculomotor nerve root fibers. They give rise to a long ascending fiber system arborizing in the striatum, and this system appears homologous to the mesostriatal CA pathway of amniotic vertebrates. At diencephalic levels a multitude of CSF‐contacting cells of both CA and 5‐HT types occurs. They abound particularly in the ventral thalamus, along the infudibular recess, in the dorsal infundibular nucleus, and in the ventral thalamus. As a whole, this population of CSF‐contacting MA cells is considered homologous to the paraventricular organ present in all nonmammalian vertebrates. Some CA cells also occur along the preoptic recess, around the hippocampal commissure, and even within the caudalmost aspect of the medial pallium. The presence of CA cell bodies among telencephalic cell groups has not been demonstrated in other vertebrates. The heaviest CA innervation in the telencephalon is found in the neuropil of the corpus striatum and in the “prominentia ventralis” (nucleus accumbens septi), both of which also stain significantly for cholinesterases. Finally, numerous CA cells are scattered throughout the magnocellular, molecular, and granular cell layers of the olfactory bulb. These cells provide a strong CA innervation to the glomerular layer of the bulb which also exhibits a high cholinesterase activity seemingly derived from the processes ofperiglomerular cells. Thus, the pattern of organization of MA systems inNecturusappears unique in many aspects, but it also displays striking similarities to the arrangement of brain MA neurons disclosed i

ISSN:0092-7317    

DOI:10.1002/cne.902110104

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe neuropeptide substance P is a transmitter candidate for certain primary afferent fibers which terminate in the substantia gelatinosa. In this study the light and electron microscopic localization of substance P in the substantia gelatinosa of the spinal trigeminal nucleus of the rat has been studied using immunocytochemical procedures.Substance P immunoreactive fibers were observed mainly in lamina I and outer lamina II. Ultrastructural analysis revealed immunoreactivity in unmyelinated fibers and in axon terminals which contained agranular spherical vesicles and large dense‐cored vesicles and which made predominantly simple asymmetric axodendritic synaptic contacts. Immunoreactive terminals only rarely formed the central terminal of synaptic glomeruli and in only one example was a stained terminal possibly postsynaptic to an unstained terminal. The majority of synapses were onto small dendrites in outer lamina II and in some cases these dendrites were themselves presynaptic to other dendrites. Immunoreactive terminals also synapsed with the soma and proximal dendrites of large neurons on the border of laminae I and II.The results show that there are at least two distinct targets for substance P immunoreactive terminals in the substantia gelatinosa, namely the large lamina I neurons and lamina II probable intemeurons. Some of the former may be projection neurons while some of the latter may correspond to the inhibitory islet cells described by Gobel and colleagues in the cat. In addition the results indicate that few substance P immunoreactive terminals receive axoaxonic synapses and emphasize instead the role of postsynaptic interactions. In particular the results suggest several sites at which substance P might interact postsynaptically with the neuropeptide enkephali

ISSN:0092-7317    

DOI:10.1002/cne.902110105

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractTo obtain a comprehensive map of the brainstem and spinal cord areas that project to the mesencephalic central gray small injections of hors‐radish peroxidase were made into various regions of the periaqueductal gray in a series of monkeys.Despite the fact that different regions of the central gray were injected in separate animals, the majority of the brainstem areas containing retrogradely filled neurons remained the same. Labeled neurons were observed in the superior colliculus, periaqueductal gray, lateral parabrachial, locus coeruleus, nucleus raphe magnus and pallidus, and a variety of brainstem reticular nuclei.In contrast to labeled brainstem areas, where labeled neurons were present predominantly ipsilateral to the injection site, the spinal trigeminal nucleus pars caudalis and the spinal cord displayed labeled cells chiefly on the side contralateral to the injection. Also in contrast to the labeled brainstem sites, where medial and lateral injection sites produced a similar pattern of labeling, medial injections in the PAG labeled almost exclusively neurons in the deep laminae (V‐X) in the spinal trigeminal nucleus pars caudalis and spinal cord while more lateral injections labeled neurons in both the deep (V‐X) and superficial (I) laminae. No consistent differences were noted in the location of labeled neurons in either brainstem or spinal sites after dorsal vs. ventral injections or caudal vs. rostral injection sites.The present study has demonstrated that the central gray receives afferent projections from a number of brainstem and spinal areas which are known to be involved in the modulation andor conduction of nociception, while other inputs are probably involved in the regulation of visceral functions. These data support the hypothesis that the mesencephalic periaqueductal gray functions as a visceral, nociceptive, and cognitive integ

ISSN:0092-7317    

DOI:10.1002/cne.902110106

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe afferent connections of the hypothalamic suprachiasmatic nucleus (SCN) of the golden hamster were examined using horseradish peroxidase (HRP) as the retrograde tracer molecule. Unilateral iontophoretic deposition of HRP into the SCN labeled ganglion cells bilaterally in the retinae. The labeled ganglion cells all had large somata and were randomly distributed across the retina. A similar number were labeled in each retina, which contrasted with the findings from injections into the optic chiasm and lateral geniculate body. Chiasm and geniculate injections both labeled three classes of ganglion cell (small, large, and giant) predominantly in the contralateral retinae.Telencephalic afferent projections to the SCN included the ventral subicular cortex and the septum. Notable diencephalic afferents included the dorsal lamina of the internal division of the ventral lateral geniculate nucleus (vLGN); the ipsilateral input was twice that of the contralateral projection. The same region of the vLGN was also noted to be reciprocally connected to the contralateral vLGN. The thalamic paraventricular nucleus was also heavily labeled but only ipsilaterally. Of functional significance, the SCN was discovered to innervate its contralateral homologue. Other less numerous afferents in the midbrain included the dorsal and median raphe nuclei and the dorsal nucleus of the lateral lemniscus.The afferent projections to the SCN determined in this study are discussed in regard to the known physiological role of the SCN as part of the circadian clock system.

ISSN:0092-7317    

DOI:10.1002/cne.902110107

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractTransganglionic transport of horseradish peroxidase (HRP) has been used to study the cell bodies and central projections of neurons innervating the vibrissae in the rat. These can be grouped into five horizontal rows and one posterior vertical row. Twenty‐four to 48 hours after the nerves innervating different vibrissae were exposed to HRP, the trigeminal ganglia, brainstem, and upper cervical spinal cord were fixed by perfusion and serial sections were processed according to the tetramethylbenzidine technique.The results revealed a tendency for somatotopic organization in the trigeminal ganglion of cell bodies innervating the different vibrissae. Corresponding termination areas in the trigeminal sensory nuclei showed a detailed pattern of organization replicating the peripheral organization of the vibrissae. In all trigeminal sensory nuclei the horizontal rows are represented in an inverted fashion from dorsal to ventral, i.e., the most dorsal row is represented most yentrally. In addition, the more anterior a vibrissa is located, the deeper is it represented in the rostral nonlaminated nuclei. The situation is reversed in the laminated nucleus caudalis. The posterior vertical row is represented most superficially in the rostral nonlaminated nuclei, but most deeply in the laminated nucleus caudalis. In nucleus cau dalis there are also rostrocaudal differences in the representation of differ ent vibrissae. Thus, the posterior vibrissae in a horizontal row have their main representations more caudally than the anterior vibrissae. The pos terior vertical row has its main representation most caudally, in the Cl segmen

ISSN:0092-7317    

DOI:10.1002/cne.902110108

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractKainic acid has been described as a highly specific neurotoxin that when injected locally into the nervous system destroys neuronal perikarya but spares axons of passage and terminals in the vicinity of the injection site. The effects of injection of this agent into the rat dorsal lateral geniculate nucleus on geniculocortical and corticofugal pathways have been examined. Neuronal perikarya were absent from injected geniculates, and products of neuronal degeneration were observed in the external stratum of the optic radiation and in layer IV of striate cortex. Furthermore, no visually driven units could bu found in physiological recordings from ipsilateral visual cortex, and no orthograde axonal transport of radioactivity to cortex was de tectable by autoradiography. These observations are consistent with the complete destruction of the geniculocortical pathway. On the other hand orthograde axonal transport appeared normal in corticogeniculate and cor‐ticotectal neurons on the injected side. In addition to silver grains appearing over the geniculate and superior colliculus label was observed over corti cofugal axons in the internal stratum of the optic radiation. It is noteworthy that axons of the corticofugal pathways are clearly segregated from geniculocortical axons over a part of their course through white matter. Corticogeniculate neurons on the injected side were able to transport D‐aspartate but not nuclear yellow retrogradely to cell bodies in layer VI. These results are consistent with the notion that cortical neurons terminating in and passing through the kainate lesion site survive but suggests, however, that corticogeniculate neurons may be functionally altered by these lesi

ISSN:0092-7317    

DOI:10.1002/cne.902110109

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902110101

出版商:Alan R. Liss, Inc.    

年代:1982

数据来源: WILEY