摘要:

AbstractThe present study demonstrates the organization of a thalamocortical projecting system which terminates within layer I of the visual cortex in the hooded rat. Horseradish peroxidase (HRP) injections restricted to layer I resulted in retrograde labeling of large and medium‐sized multipolar and fusiform neurons that are located within the ventromedial (VM) nucleus and a dorsomedial subunit of the ventral anterolateral nucleus (VAL). Retrograde cellular labeling also occurs within the anteromedial nucleus (AM) following these injections. After restriction of HRP injections to layer I, peroxidase labeling was not found within neurons of the classically defined intralaminar system, i.e., central medial, paracentral, and central lateral nuclei, or within the rostral continuations of the intralaminar system. Since the VM, dorsomedial VAL, and AM nuclei are directly adjacent to portions of the internal medullary lamina, we refer to this amalgam of rostral thalamic nuclei that project to layer I as the “paralaminar” system. We also provide cytoarchitectonic criteria that can be used to distinguish three separate subdivisions within the VAL complex, including that portion of the VAL which is part of the “paralaminar” system. In contrast, when control injections of WGA‐HRP are placed within either the cellular supragranular or infragranular layers of the visual cortex, no appreciable number of neurons are labeled within the VM,

ISSN:0092-7317    

DOI:10.1002/cne.902340202

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

年代:1985

数据来源: WILEY

摘要:

AbstractWe have examined the location of cholinergic and non‐cholinergic neurons that project to the rat basolateral amygdaloid nucleus by using choline acetyltransferase (ChAT) immunohistochemistry in combination with retrograde fluorescent tracing on the same tissue section. Since many tracer‐and ChAT‐positive neurons were identified in basal forebrain areas, including the ventral pallidum, we also stained many of the sections for glutamate decarboxylase, a suitable marker for the delineation of pallidal areas.Cholinergic neurons projecting to the basolateral amygdaloid nucleus were observed in a continuous territory stretching from the dorsal part of ventral pallidum, through sublenticular substantia innominata to ventral parts of globus pallidus and peripallidal areas. Non‐cholinergic neurons projecting to the basolateral amygdaloid nucleus were found intermixed within the same structures and constitute approximately 25% of the amygdalopetal projection neurons in these ventral forebrain structures.Since amygdalopetal cholinergic neurons were demonstrated in areas generally recognized as giving rise to cholinergic projections to cerebral cortex, several retrograde double‐labeling experiments with two different fluorescent tracers were performed for the purpose of detecting the possible existence of collateral projections. The results obtained showed that the cholinergic basal forebrain neurons in general project to only one forebrain region, and, furthermore, that the cholinergic system consists of partially overlapping subsets of neurons that project to various neocortical and allocortical areas and to the amygda

ISSN:0092-7317    

DOI:10.1002/cne.902340203

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe organization of the fourth abdominal ganglion of the crayfish,Procambarus clarki, was studied with the light microscope in serial sections stained with osmium ethyl gallate. This ganglion is composed of a ventral rind of somata and a core of alternating layers of through‐tracts and commissures. The longitudinal tracts of the ganglion are named according to the system in use for the orthopteran insects, because the basic plans of the crustacean and insect ventral ganglia exhibit striking anatomical parallels. The dorsal tracts are the largest and the most regular in their path through the ganglion. In the ventral posterior quadrant of the ganglion the tracts diverge from the basic plan to pass around the major synaptic neuropil and the bases of the peripheral nerves.This paper reports the three‐dimensional anatomy of the major longitudinal through‐tracts, internal tracts and commissures, and bases of peripheral nerves. Landmark features of the ganglion–including the tracts, the major artery of the vascular system, the shape of the ganglionic core in section, and prominent single cells, all of which make it possible to recognize specific regions of the ganglion–are

ISSN:0092-7317    

DOI:10.1002/cne.902340204

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

年代:1985

数据来源: WILEY

摘要:

AbstractFour discrete regions of synaptic neuropil in the crayfish fourth abdominal ganglion are described by light and electron microscopy. The largest is thehorseshoe neuropil, a horseshoe‐shaped mass of synaptic glomeruli that lies horizontally in the ventral ganglionic core. This neuropil has a substructure of three rings of fused glomeruli associated with the entry of small axons from the first and second nerve roots. Thelateral neuropilsare large, paired bulges of neuropil that define the sides of the ganglionic core. They contain neuronal profiles of various sizes, filled with clear or dense‐cored vesicles. The neurons are randomly oriented except for occasional dendritic bundles. Thetract neuropilis ultrastructurally similar to the lateral neuropils but it is distributed among the largest axons of the through‐tracts and commissures. Themidline neuropilsare small, U‐shaped clumps of uniformly sized neuronal profiles that contain large numbers of dense‐cored vesicles and distinctive lamellar i

ISSN:0092-7317    

DOI:10.1002/cne.902340205

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

年代:1985

数据来源: WILEY

摘要:

AbstractThis study utilized peroxidase cytochemical methods to survey and analyze the distribution, morphology, and functional relationship of the various components of sensory nerve endings in a focal region of the anterior hard palate (incisive papilla) of the rat. The studies included an anatomical survey of this relatively unknown oral structure, confirmation of the trigeminal origin (labeled by retrograde axonal transport of WGA‐HRP injected into the incisive papilla) of the sensory nerve endings, and a complete analysis of the distribution of these nerve endings (labeled by anterograde axonal transport of HRP or WGA‐HRP injected into the trigeminal ganglion). Three methods of fixation and two methods of cytochemical reaction were used for selection of an optimal technique for these studies. The results showed distinct patterns of peroxidase‐labeled sensory nerve endings at three regions of the incisive papilla: (a) dome region (ventral), where labeled nerve endings formed three parallel channels in association with three surface ridges; (b) chemosensory corpuscle enriched region (medial to incisive canal), where 82% of the 30–40 chemosensory corpuscles were labeled; and (c) lateral labium (lateral to incisive canal), where labeled nerve endings formed a circumscribed network guarding the orifice of incisive canal. The discrete organization of multiple sensory nerve endings in the incisive papilla of the rat may provide an easily accessible model system for various studies in sensory phy

ISSN:0092-7317    

DOI:10.1002/cne.902340206

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe ultrastructure and identification of WGA‐HRP‐labeled sensory receptors in the rat incisive papilla (the most anterior part of hard palate) were studied using semiserial thin sections. Various sensory receptors were organized according to three locations: dome region (ventral), chemosensory corpuscle region (medial to orifice of incisive canal), and lateral labium (apposing the incisive canal). In the dome region, the sensory receptors were localized in three sensory zones that were associated with surface ridges (one medial and two lateral). In each of these zones, intraepithelial receptor axons and Merkel receptors occurred in the epithelium, while simple unencapsulated corpuscles, glomerular‐Meissner corpuscles, and incisive (encapsulated) corpuscles occurred in the lamina propria. In the chemosensory corpuscle region, chemosensory corpuscles and intraepithelial receptor axons were located in the epithelium, and incisive corpuscles were present in the lamina propria. In the lateral labium, only intraepithelial receptor axons were prominent. In all these sensory receptors, the preterminal axons and axon terminals were labeled with the tracer protein. In addition, some nonneuronal cells closely associated with the axon terminals were selectively labeled, e.g., terminal Schwann cells, lamellar Schwann cells, Merkel cells, corpuscular basal cells, and chemosensory cells. Other adjacent cells were not labeled, e.g., unspecialized epithelial cells, capsular cells, corpuscular sustentacular cells, and fibroblasts. In both labeled axons and cells, WGA‐HRP was incorporated into vesicles, tubules, and vacuolar organelles. The specific intercellular transfer of tracer protein may indicate trophic interactions between axon terminals and support cells in sensory receptors. The specific organization of multiple sensory receptors in the rat incisive papilla may provide a useful alternative system for studying somatosensory phy

ISSN:0092-7317    

DOI:10.1002/cne.902340207

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe pyramidal cells in area 17 of rat visual cortex have been examined by light microscopy using Golgi preparations and semithin plastic sections, and by electron microscopy. Pyramidal cells have cell bodies in layers II–VIa. The pyramidal cells in the lower portion of layer II/III are typical examples of this neuronal type in that they have pyramidal‐shaped cell bodies, apical dendrites which ascend to layer I, and a skirt of basal dendrites. The pyramidal cells in upper layer II/III are similar in form but have shorter apical dendrites, while the most superficial pyramidal cells lack apical dendrites and instead have two or more primary dendrites that emanate from the upper surface of their somata. In layer V the pyramidal cells are of two sizes, medium and large, and both have a typical morphology, although the larger neurons have thicker apical dendrites and better‐developed axon hillocks than the medium‐sized pyramids. The medium‐sized pyramidal cells of layer V outnumber the large ones to a ratio of 2.5:1. In layer IV a few typical medium‐sized pyramidal cells are present, but the majority are small and can be regarded as star pyramids for they have dendrites radiating in all directions. No clearly identified spiny stellate cells have been encountered in layer IV. The pyramidal cells of layer VIa are also small, and most of them have apical dendrites which only ascend as far as layer IV. In addition to these varieties, both inverted and horizontally inclined pyramidal cells have been encountered.In electron micrographs it is apparent that although all of the pyramidal cells have symmetric axosomatic synapses, the frequency with which these synapses occur varies. The cell bodies of the various forms of pyramidal cells do not show a standard cytology. The medium‐sized pyramidal cells of layer II/III usually have rounded nuclei, while the nuclei of the small pyramidal cells of layers IV and VIa are somewhat more irregular, and the large pyramidal cells of layer V have deeply indented nuclear envelopes. The appearance of the perikaryal cytoplasm also varies. The larger pyramidal cells have numerous mitochondria and well‐developed Nissl bodies in their perikaryal cytoplasm, but the smaller cells have much‐less‐pronounced mitochondria and their rough endoplasmic reticulum is only organized into stacks at the bases of dendrites.Pyramidal cells account for about 87% of profiles of neuronal cell bodies with nuclei in layer II/III, 90% in layer IV, 89% in layer V, a

ISSN:0092-7317    

DOI:10.1002/cne.902340208

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

年代:1985

数据来源: WILEY

摘要:

AbstractIn the preceding article the characteristics of the various types of pyramidal cells present in area 17 of rat visual cortex were described (Peters and Kara, '85). In the present article the nonpyramidal cell population of this cortex is considered. It is known from Golgi preparations that in layers II–VIa there are bipolar cells, smooth or sparsely spinous multipolar and bitufted cells with either unmyelinated local plexus or myelinated axons, and chandelier cells. Each of these cell types has been previously examined in Golgi‐electron microscopic preparations. The question now being asked is whether the information about the characteristics of these different types of nonpyramidal cells derived from the Golgi‐electron microscopic studies can be used to identify the cell bodies of nonpyramidal cells in tissue prepared for conventional electron microscopy. If this can be done then the neuronal composition of area 17 can be determined.It has been found that the cell bodies of bipolar cells can be readily identified because they are elongate and have nuclei with a vertical infolding and few axosomatic synapses, which are of both the symmetric and asymmetric varieties. Evidence is presented to show that there are two types of bipolar cells, small ones and large ones, the large ones being distinguished by their well‐developed endoplasmic reticulum in which the cisternae are arranged parallel to the cell surface. Bipolar cells account for 6% of the neuronal profiles in layer II/III, 3% in layer IV, 5% in layer V, and 2% in layer VIa.The cell bodies of other types of nonpyramidal cells in layers II–VIa cannot be distinguished from each other in thin sections, because recognition of the different cell types depends upon the characteristics and distribution of their dendrites and axons. However, it is evident that in this group of neurons there are some with small cell bodies and others with large cell bodies, and in both size groups there are varieties of neurons which can be recognized from the characteristics of their perikaryal cytoplasm. All of these neurons have both symmetric and asymmetric axosomatic synapses. The greatest number of these nonpyramidal cells which are not bipolar in form is found within layer II/III, where they account for 7% of all neuronal profiles. These neurons comprise 4% of all neuronal profiles in layer IV, 6% in layer V, and 2% in layer VIa.Layers I and VIb contain only nonpyramidal cells, but these are different from the ones in layers II–VIa.Overall, bipolar cells account for 4% of the neuronal profiles encountered in layers II–VIa, and the other nonpyramidal cells account for 6% of the neuronal population. Consequently, in these layers 90% of the neurons are pyramidal cells. These results are considered in relation to analyses of the neuronal population of rat area 17 carried out by previous authors, and in the context of information about the disposition and frequency of nonpyramidal cells derived from the use of antibodies to potential neur

ISSN:0092-7317    

DOI:10.1002/cne.902340209

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe pretectal nucleus lentiformis mesencephali (nLM) ofRana pipienswas investigated with autoradiographic, horseradish peroxidase (HRP), and Golgi techniques. Retinal afferents to nLM originate primarily from the central retina. The primary projection is contralateral with a small ipsilateral component. Following optic nerve transection and HRP impregnation, contralateral retinal afferents show a restricted, dense core of HRP label in the superficial portion of the nucleus with sparser HRP label in the surround. Ipsilateral retinal afferents arborize throughout nLM,exceptin the dense‐core region. Additional afferents to nLM originate from the ipsilateral tectum, the nucleus rotundus, the mesencephalic pretectal gray, the contralateral nLM, and the nucleus of the basal optic root. Afferents from the accessory optic system arborizeonlyin the dense‐core region, following HRP injections into the nucleus of the basal optic root, while afferents from the mesencephalic pretectal gray arborize in all parts of nLMexceptthe dense core. Afferents from the tectum and anterior thalamus appear to arborize throughout the nucleus without discernible pattern.The lamination of afferent terminals in nLM was correlated with Nissl‐stained cytoarchitectural material in which the majority of large neurons cluster around the dense core of nLM. Three types of neurons occur in nLM: large neurons (25‐μm dia.), fusiform neurons (12.5‐μm dia.), and stellate neurons (10‐μm dia.). Additionally, two cell groups outside nLM which send dendrites into the nucleus were observed: cells of the posterior lateral nucleus and cells of the posterior thalamic pretectal gray. Both large and fusiform neurone project to the deep layers of the optic tectum as well as to the ventral rhombencephalon superficial to the abducens nucleus. While a small number of fusiform neurons project to the nucleus of the basal optic root, the stellate neurons appear to be intrinsic to nLM.The anuran nLM strongly resembles the nucleus of the optic tract in mammals in terms of the site of origin of its retinal afferents, lamination of afferent terminations, its central connections, and its demonstrated involvement in horizontal optokin

ISSN:0092-7317    

DOI:10.1002/cne.902340210

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.902340201

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

年代:1985

数据来源: WILEY