摘要:

AbstractHistochemical techniques have been used to examine the development of the enzyme acetylcholinesterase (AChE) in normal and transplanted rat superior colliculus (SC). At birth (P0), relatively little AChE activity was found in SCin situ; however, there was a gradual increase in the intensity of AChE staining in the SC over the first 4 postnatal weeks. In the superficial layers, an increase in AChE activity was first seen in rostromedial SC at P6 and was found throughout the upper tectal layers by P10. An increase in AChE activity in the intermediate layers was apparent by P12 and the adult pattern, characterized by periodic bands of AChE staining, was established by P22.In tectal grafts, the development of AChE activity followed a time course similar to that found in normal SC. Mature tectal grafts contained moderate AChE activity with AChE‐positive cells scattered throughout the neuropil. There were however, localized, often spherically shaped areas which displayed relatively intense AChE activity. These AChE‐dense areas had a characteristic appearance in adjacent sections stained for Nissl or neurofibrils. Significantly, host retinal input, where present, was always restricted to the AChE‐dense regions and it seems certain that these areas are homologous to the superficial layers of normal SC. AChE‐rich regions were also present, however, in grafts which received no retinal input and in general the pattern of AChE activity in tectal grafts was strikingly similar, irrespective of their location or connections with the host brain. It would appear, therefore, that much of the AChE activity in tectal transplants, and presumably in SCin situ, is intrinsic to that region and not derived from or dependent upon extrinsic inne

ISSN:0092-7317    

DOI:10.1002/cne.902400202

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

年代:1985

数据来源: WILEY

摘要:

AbstractGlial markers, namely antibodies to glial fibrillary acidic protein (GFAP), vimentin, galactocerebroside (GC), and 08 antigen, were used to study the occurrence and location of neuroglial cells in adult rabbit retinae. Müllerian glia were vimentin‐positive, lacked detectable amounts of GFAP, and were found in all parts of the rabbit retina. The neuronal A‐type horizontal cells were labeled by vimentin antibody only in the superior retina and at the medullary rays but not in the inferior retina. They lacked GFAP in all regions. Astroglia showing GFAP and vimentin immunoreactivity were absent from most of the superior and inferior retina, being found only in the myelinated area of the ganglion cell axon bundles, the medullary rays. Thus the rabbit retina differs from the retinae of all mammals studied to date by this restriction of astroglia to just one area. The medullary rays, which are known to be myelinated, were labeled by the antibodies to GC and 08 antigen.Boycott and Hopkins ('84) found, using whole‐mounted rabbit retinae stained by the reduced silver method of Richardson, that all neurons in the ganglion cell layer of the rabbit retina have a cilium, while cells that have only a diplosome are either neuroglia or microglia. By using this criterion as a basis to differentiate between neurons and glia, the absence of neuroglia from the nerve fiber layer outside the medullary rays was confirmed in the same silver‐stained material. Thus, the data obtained from immunocytochemistry and conventional silver staining agree closely. It has been concluded that, at least in the adult, significant lengths of ganglion cell axons extend without astroglial

ISSN:0092-7317    

DOI:10.1002/cne.902400203

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe fine structure of synaptic terminals contacting neurons generated in the forebrain of adult male canaries was investigated by autoradiography and electron microscopy. The procedure for labeling the new neurons included pretreating adult canaries with3H‐thymidine and sacrificing them 23–45 days later. Neurons were identified as newly generated by the presence of3H‐thymidine in the cell nucleus. The new neurons in the nucleus hyperstriatum ventralis, pars caudalis (HVc) were identified by autoradiography and light microscopy and examined with electron microscopy.Several types of synaptic terminals contacted the cell body and proximal dendrites of the newly formed neurons. Synaptic junctions were formed by terminals that contained (1) spherical, agranular vesicles, (2) large densecore vesicles and spherical, agranular vesicles, and (3) pleomorphic or flattened synaptic vesicles. Terminals that contained spherical vesicles were most often associated with asymmetric synaptic densities, and terminals that contained pleomorphic or flattened vesicles formed symmetric junctions. New neurons were also contacted by small terminals that contained few vesicles and had little pre‐ or postsynaptic density associated with the junction; these terminals may be a special type or may be in the process of developing their synaptic contact with the new neuron. In addition, rare terminals that appeared to be degenerating or to contain debris from other degenerating neural elements contacted new neurons. In summary, these data indicate that the new neurons, which are known to be inserted into existing neural networks, receive synaptic input from at least three different

ISSN:0092-7317    

DOI:10.1002/cne.902400204

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

年代:1985

数据来源: WILEY

摘要:

AbstractWe studied afferents to the parabrachial nucleus (PB) from the spinal cord and the spinal trigeminal nucleus pars caudalis (SNVc) in the rat by using the anterograde and retrograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP). Injections of WGA‐HRP into medial PB retrogradely labeled neurons in the promontorium and in lamina I of the dorsal rostral SNVc, while injections into lateral PB and the Kölliker‐Fuse nucleus retrogradely labeled neurons in these areas as well as in lamina I throughout the caudal SNVc and spinal dorsal horn. Injections of WGA‐HRP into the caudal SNVc and dorsal horn of the spinal cord resulted in terminal labeling in the dorsal, central, and external lateral subnuclei of PB and the Kölliker‐Fuse nucleus, all of which are known to receive cardiovascular and respiratory afferent information. Injections of WGA‐HRP into the promontorium and dorsal rostral SNVc resulted in terminal labeling in the same PB subnuclei, as well as in the medial and the ventral lateral PB subnuclei, which are sites of relay for gustatory information ascending from the medulla to the forebrain. The spinal and trigeminal projection to PB may mediate the convergence of pain, chemosensory, and temperature sensibilities with gustatory and cardiorespiratory

ISSN:0092-7317    

DOI:10.1002/cne.902400205

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe location and number of motoneurons to individual pinna muscles were determined by retrograde transport of horseradish peroxidase in rat and flying fox. The degree of ear mobility differs considerably between these species in that rats perform simpler ear movements while flying foxes move their pinnae in a sophisticated way. Five pinna muscles were investigated in each species. Motoneurons lay within the medial subdivision of the facial motor nucleus extending over its entire rostrocaudal length. They were topographically organized; however, a somatotopic order could not be observed. With one exception homologous pinna muscles were represented in corresponding areas in both species, supporting the idea of a common representation of ear muscles in mammals. In rat, motoneuron pools overlapped considerably, whereas in flying fox overlap was minute. A total of 1,110 and 1,646 motoneurons were labeled in rat and flying fox, respectively. We conclude that the higher number of pinna motoneurons in the latter species in addition to the more clear‐cut topography provide the structural substrates that underlie differences in the quality of ear movements as seen in bats vis‐a‐vis other ma

ISSN:0092-7317    

DOI:10.1002/cne.902400206

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe trigeminal and glossopharyngeal ganglia of the adult mallard were studied following HRP injections into the principal trigeminal nucleus (PrV). The PrV consists of the principal trigeminal nucleus proper (prV) and the principal glossopharyngeal nucleus (prIX). After an injection into the prV, the labeled cells were found in the ipsilateral trigeminal ganglion. After an injection into the prIX, labeled cells were found in the ipsilateral distal glossopharyngeal ganglion, but not in the proximal ganglion of the IX and X cranial nerve (pGIX + X).In Nissl preparations, two types of ganglion cells in the trigeminal ganglion, pGIX + X, and distal ganglion of N IX could be distinguished: larger light cells and smaller dark cells. We could not determine whether the HRP‐labeled cells belonged to both types or to one of them; but because all the labeled cells were over 20 μm, we concluded that the smallest cells (10–19 μm) in the trigeminal ganglion and distal ganglion of N IX did not project to the PrV.The labeling of the cells in the distal ganglion of N IX (average 34.5 μm) was uniformly moderate. In the trigeminal ganglion there were two types of labeled cells: heavily labeled cells (average 29.1 μm) and moderately labeled cells (average 35.1 μm). These two types of labeling (moderate and heavy) may reflect two types of primary sensory neurons: cells with ascending, nonbifurcating axons, and cells with bifurcating axons. We speculate that the former are proprioceptive neurons and the latter tactile neurons. Labeled bifurcating axons in the sensory trigeminal complex gave off collaterals to all parts of the descending trigeminal nucleus except to the caudalmost laminated spi

ISSN:0092-7317    

DOI:10.1002/cne.902400207

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe distribution of the projection from one cochlear nucleus (CN) within each inferior colliculus (IC) was studied in adult, normal gerbils and adult gerbils subjected to unilateral ablation of the contralateral cochlea at 2 days of age. The projection was studied by using the Fink‐Heimer technique for impregnating degenerating axons and their terminal processes with silver. Following an extensive, unilateral lesion of the CN, degeneration was seen in both ICs of all animals. In normal animals, degeneration was both more widespread and heavier in the contralateral than in the ipsilateral central nucleus of IC (ICC). Degeneration was most widespread in the rostral and lateral parts of both ICCs and in the ventral part of the contralateral ICC. Degeneration was observed in 26% of the area examined in ipsilateral ICC and in 73% of the area examined in contralateral ICC. In cochlea‐ablated animals there was a much greater similarity in the area of degeneration in the ICC ipsilateral (57%) and contralateral (67%) to the CN lesion. The same regional distributions of degeneration were observed as in the normal animals except that the distribution of degeneration in the ipsilateral ICC more closely resembled the normal contralateral than the normal ipsilateral profile. We conclude that the normal distribution of projections from the CN within the ipsilateral ICC is substantially modified by neonatal ablation of the contralateral choch

ISSN:0092-7317    

DOI:10.1002/cne.902400208

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe organization of the corticocuneate pathway was investigated in monkeys by using the anterograde and retrograde axonal transport of either horseradish peroxidase (HRP) or wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP).Injection of either tracer into the precentral cortex (centered on area 4) results in heavy anterograde labeling in the tegmental region, which lies immediately ventrolateral to the cuneate nucleus, particularly at levels caudal to the obex. On the other hand, injections of the same tracers involving areas 3b, 1, and 2 cause anterograde labeling mainly within the core (pars rotunda of Ferraro and Barrera, '35, Arch. Neurol. Psychol.33:262–75) of the cuneate nucleus. Anterograde labeling is also evident in the rostral parts of the cuneate nucleus, especially after injections involving areas 1 and 2. Injections restricted largely to area 3b cause anterograde labeling preferentially in the core of the cuneate nucleus.After injection of HRP or WGA‐HRP into the dorsal medulla, retrogradely labeled neurons are present both in the pre‐ and postcentral gyrus, but their location depends upon the sites and extent of the injection site. When the tracer diffuses into the underlying tegmental area, many retrogradely labeled neurons appear in the precentral motor cortex, principally in area 4 although some of them also occur in area 6. With smaller injections, largely restricted within the cuneate nucleus, most labeled neurons are present in the postcentral gyrus, with the largest population in areas 1 and 2; a smaller number of small neurons in area 3b are best demonstrated with WGA‐HRP; and area 3a contains the smallest complement of retrogradely labeled neurons.The data from these studies suggest a segregation of pre‐ and postcentral afferents in the ventral tegmental region and the cuneate nucleus, respectively. These findings pertaining to the corticocuneate projection in the monkey are discussed in relation to (1) the parallelism between monkeys and cats (2) possible physiological implications of the anatomical organization described, and (3) conflicting evidence in the neurophysiological observations obtained, by earlier investigators, by antidromic and orthodromic activation of t

ISSN:0092-7317    

DOI:10.1002/cne.902400209

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe perikaryal projections of the neurons in the thoracic spinal ganglia of gecko and lizard usually appear as finger‐shaped evaginations running roughly parallel to the surface of the nerve cell body; they show a nearly circular cross section with a rather uniform transverse diameter having an average value of about 0.2 μm. In both gecko and lizard a very high correlation was found between the surface area of perikaryal projections and both the volume and smoothed surface area of the corresponding nerve cell body.The results of the present research agree with those obtained in a previous study on two mammal species (cat and rabbit) and lend further support to the hypothesis advanced in that study; i.e., that perikaryal projections in sensory ganglion neurons are normal formations which maintain the surface‐to‐volume ratio above the critical level for metabolic exchanges.Perikaryal projections increase the surface area of the nerve cell body by 32.5% in gecko and 30% in lizard, while they increase it by 43% in cat and 39.5% in rabbit. This difference may be related to the lower metabolic rate of the neurons in poikilotherms than in m

ISSN:0092-7317    

DOI:10.1002/cne.902400210

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

年代:1985

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902400201

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

年代:1985

数据来源: WILEY