摘要:

AbstractLaser scanning confocal microscopy was employed to map the distribution of integrin immunoreactivity at the photoreceptor‐retinal pigment epithelial (RPE) interface of the primate retina, and to determine its relationship to the actin cytoskeleton. Immunolabeling using a polyclonal antibody to the human vitronectin receptor (VnR), a heterodimer containing the αv subunit in combination with either the β3 or β5 subunits, is detected primarily on the apical surface of the retinal pigment epithelium (RPE) in vivo and in vitro. It is also associated with the photoreceptor inner and outer segment cell surfaces. In contrast, immunolabeling using a polyclonal antibody to the human fibronectin receptor (FnR), a heterodimer containing the α5 and β1 subunits, is detected principally on the basolateral surface of the RPE and is virtually absent in photoreceptors. A partial three‐dimensional reconstruction of the anti‐VnR labeling pattern in cone photoreceptors reveals cell surface labeling that originates at the level of the myoid just distal to the outer limiting membrane. It extends distally toward the ellipsoid and terminates at the level of the cone outer segment. Approximately 20–22 immunoreactive foci are distributed evenly around the perimeter of the cone ellipsoid. These foci correspond in number and location to the calycal processes that protrude from the distal portion of the ellipsoid. A double‐labeling procedure, employing VnR antibody and a fluorescently labeled phallotoxin (phalloidin), was used to identify regions of VnR co‐distribution with filamentous actin (F‐actin). One such region includes the VnR‐immunoreactive foci at the margins of the cone inner segments and the actin cables that course through the photoreceptor ellipsoid and terminate within the calycal processes. A second zone of co‐distribution coincides with the actin‐containing, circumferential bundle at the lateral borders of the RPE cells, and a third zone is associated with the apical microvilli of the RPE that ensheath cone outer segments. In order to help identify the specific subunits underlying VnR (αvβ3/5) immunoreactivity, Northern blots of retinal‐RPE RNA were probed with α32P‐cDNAs to the human αv, β3, and β5 subunits and additional immunolocalization studies were performed using integrin human α or β subunit‐specific antisera. The results from these studies strongly suggest that one or more integrins, containing the αv and/or β5 subunits, are expressed by the photoreceptors and RPE. It thus appears likely that an integrin(s) from the cytoadhesin family located on the plasma membranes of these cells participates in some adhesion‐related event(s) at the interface between the neurol

ISSN:0092-7317    

DOI:10.1002/cne.903600102

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe superior olivary complex is the first site in the central auditory system where binaural interactions occur. The output of these nuclei is direct to the central nucleus of the inferior colliculus, where binaural inputs synapse with monaural afferents such as those from the cochlear nuclei. Despite the importance of the olivary pathways for binaural information processing, little is known about their synaptic organization ir the colliculus. The present study investigates the structure of the projections from the lateral and medial superior olivary nuclei to the inferior colliculus at the electron microscopic level. Stereotaxic placement and electrophysi ological responses to binaural sounds were used to locate the superior olive. Anterograde axonal transport of 3H‐leucine was combined with light and electron microscopic autoradiography to reveal the location and morphology of the olivary axonal endings.The results show that the superior olivary complex contributes different patterns of synaptic input to the central nucleus of the inferior colliculus. Each projection from the superior olivary complex to the colliculus differs in the number and combinations of endings. Axonal endings from the ipsilateral medial superior olive were exclusively the round (R) type that contain round synaptic vesicles and make asymmetrical synaptic junctions. This morpholo is usually associated with excitatory synapses and neurotransmitters such as glutamate. Endings from medial superior olive terminate densely in the central nucleus. The projection from the contralateral lateral superior olive also terminates primarily as R endings. This projection also includes small numbers of pleomorphic (PL) endings that contain pleomorphic synaptic vesicles and usually make symmetrical synaptic junctions. The PL morpholo is associated with inhibitory synapses and transmitters such as gamma‐aminobutyric acid and glycine. All endings from the contralateral lateral superior olive terminate much less densely than endings from the medial olive. In contrast, the projection from the ipsilateral lateral superior olive contributes both R and PL endings in roughly equal proportions. These ipsilateral afferents are heterogeneous in density and can terminate in lower or higher concentrations than endings from the contralateral side.These data show that the superior olive is a major contributor to the synaptic organization of the centr nucleus of the inferior colliculus. The ipsilateral projections of the medial and lateral superior olive may produce higher concentrations of R endings than other inputs to the central nucleus. Such endings may participate in excitatory synapses. The highest concentra tions of PL endings come from the ipsilateral lateral superior olive. In combination with inputs from the contralateral dorsal nucleus of the lateral lemniscus, PL endings from the superior olive may participate in many inhibitory synapses found in the central nucleus. These different patterns of synaptic input from the superior olivary complex will influence how binaural information is transmitted to the inferior colliculus. © 1995 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903600103

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe aim of the present study was to extend our knowledge of the development of catecholamine (CA) systems in the class of amphibians to the order of urodeles. In contrast to previous studies of urodeles, the present study with antisera against tyrosine hydroxylase (TH) and dopamine revealed that CA systems are already present at early embryonic stages of the newt,Pleurodeles waltlii. Although the development from fertilized egg to juvenile in the urodelePleurodeleslasts twice as long as that in the anuran,Xenopus laevis, and shows less dramatic changes in external morphology, the spatiotemporal sequence of appearance of TH‐immunoreactive cell groups is rather similar. An early appearance of TH‐immunoreactive cell bodies occurs in the olfactory bulb, the posterior tubercle, the accompanying cell group of the hypothalamic periventricular organ, the suprachiasmatic nucleus, the locus codruleus, an area immediately ventral to the central canal of the spinal cord, and in the retina.The presence of CA systems at early embryonic stages of both anurans and urodeles suggests that these systems are already of functional significance early in development. The maturation of CA neuronal structures in the olfactory and retinal circuitries, which takes place during development earlier in amphibians than in mammals, supports that notion. © 1995 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903600104

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe goal of this study was to determine the compartmental organization of 5′‐nucleotidase within the rodent ventral striatum and to compare the distribution of 5′‐nucleotidase with that of leu‐enkephalin, cell clusters, and infralimbic cortical innervation. In the core, 5′‐nucleotidase is present in several contiguous patchy structures that are in register with leu‐enkephalin compartments. In the shell, 5′‐nucleotidase is concentrated in a longitudinal band along the septal border. This “medial band” extends from the rostral pole of the ventral striatum to the bed nucleus of stria terminalis. The ventral portion of the medial band is in register with a cluster of cells, located medial to the most dorsal island of Cajella. A second 5′‐nucleotidase compartment along the border of the core and shell is in register with a cell cluster and is most evident at caudal levels of the ventral striatum. The innervation of the ventral striatum by the infralimbic cortex is denser in the shell than in the core. In the shell, fibers from the superficial layers of the infralimbic cortex tend to avoid the 5′‐nucleotidase‐rich cell clusters and terminate in areas of moderate 5′‐nucleotidase density. By contrast, fibers from the deep layers terminate in the ventral striatum without regard to the 5′‐nucleotidase‐rich cell clusters. Overall, the compartmental structure of 5′‐nucleotidase in the ventral striatum segregates projections from different layers of the infralimbic cortex. Dense 5′‐nucleotidase compartments are innervated by neurons in the deep layers of the infralimbic cortex. The area of moderate 5′‐nucleotidase density surrounding the 5′‐nucleotidase compartments is innervated by neurons in b

ISSN:0092-7317    

DOI:10.1002/cne.903600105

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThis study evaluates the distribution of receptors for platelet‐derived growth factor (PDGF) on central nervous cells maintained in vitro using colloidal gold‐labeled immunocytochemical markers at the electron microscopic level. Platelet‐derived growth factor receptors were found to be sparsely distributed over the surface of type 1 astrocytes, apparent type 2 astrocytes, and neurons. Receptors appeared to be preferentially associated with filopodia‐like extensions of the cell membrane. The existence of functional receptors was confirmed using the impermeant, water‐soluble affinity cross‐linking agent bis(sulfosuccinimidyl) suberate to covalently link radiolabeled PDGF to its receptor. The PDGF/receptor complexes could also be immunoprecipitated with the same antibody used in immunocytochemical experiments. The improved resolution of these techniques allows definitive identification of PDGF receptors on cultured mammalian central nervous system cells other than oligodendrocytes. These data expand the range of possible roles of PDGF during nervous system development. Receptors for PDGF are likely to play a key role in the differentiation of cells in the central nervous system. © 1995 Wil

ISSN:0092-7317    

DOI:10.1002/cne.903600106

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractDevelopmental patterns of electroreceptors in the wealdy electric fishEigenmanniawere investigated by histological, histochemical, immunocytochemical, cell kinetic, ultrastructural, and computer‐assisted three‐dimensional reconstruction methods. The first cell of an electroreceptor primordium is embedded in the stratum germinativum of the epidermis. An unmyelinated, afferent nerve fiber ends near this cell below the basal lamina. Protrusions and vacuole‐like inclusions at the basal lamina above the nerve fiber ending suggest a mechanism of nervous induction. The receptor primordium cell subsequently divides into a single cell layer. Within 48 hours, a second apical cell layer forms from the first, and, thus, the primordium differentiates into an apical layer of presumptive receptor cells and a basal layer of presumptive supporting cells. While the two layers further differentiate into mature receptor and supporting cells, the afferent fiber penetrates the basal lamina, sprouts, and forms a synapse with each receptor cell. Transitory fibers also project along the receptor cells to the top of the developing electroreceptor but degenerate during development. Synapses are smaller in early developmental stages compared to older stages, and pre‐ and postsynaptic vesicles are more abundant and widely distributed in younger stages. Moreover, presynaptic ribbons are longer and are interconnected at their apical ends. Supporting cells continue to divide during further maturation and form new receptor cells. The number of receptor cells per tuberous organ increases during the first 4 days of electroreceptor development and plateaus when the fish are 9 days old. It declines again when organs begin to divide into clusters. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903600107

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractPreviously, using a middle cerebral artery occlusion model in Wistar rat, we showed autonomic disturbances similar to those seen clinically and observed striking neurochemical changes in cortical and subcortical sites at 5 days following stroke. The neurochemical changes may account for functional recovery and/or autonomic disturbances after focal ischemia. To understand the possible mechanisms and to facilitate future studies, it is necessary to define the time‐courses of these changes.Using immunohistochemical staining with the peroxidase‐antiperoxidase reaction, the changes in several neuropeptides over the peri‐ischemic region and the ipsilateral central and basolateral nucleus of the amygdala were investigated at different times after middle cerebral artery occlusion. In the experimental group, neuropeptide Y immunoreactivity appeared to increase by 6 hours in the peri‐ischemic region. Using image analysis to quantify the staining intensity, the change became statistically significant at 1 day, peaked around 3 days, and subsided at 10 days. There was a delayed increase in neuropeptide Y in the ipsilateral basolateral nucleus of the amygdala with a peak around 3 days. Immunoreactive staining for leucine‐enkephalin, dynorphin, and neurotensin demonstrated an increase that was localized to the ipsilateral central nucleus of the amygdala with a peak around 3 days and a return to baseline levels by 10 days.The results support a specific time‐course for each of the neuropeptides studied and indicate that a survival time of 3 days after focal ischemia is the critical period for examining the relationship between neuropeptide responses and neuronal or functional recovery. © 1995 Wil

ISSN:0092-7317    

DOI:10.1002/cne.903600108

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have investigated the time course and extent to which peripheral nerve lesions cause a morphological reorganization of the central terminals of choleragenoid‐horseradish peroxidase (B‐HRP)‐labelled primary afferent fibers in the mammalian dorsal horn. Choleragenoid horseradish peroxidase is retrogradely transported by myelinated (A) sensory axons to laminae I, III, IV and V of the normal dorsal horn of the spinal cord, leaving lamina II unlabelled. We previously showed that peripheral axotomy results in the sprouting of numerous B‐HRP labelled large myelinated sensory axons into lamina II. We show here that this spread of B‐HRP‐labelled axons into lamina II is detectable at 1 week, maximal by 2 weeks and persists for over 6 months postlesion. By 9 months, however, B‐HRP fibers no longer appear in lamina II. The sprouting into lamina II occurs whether regeneration is allowed (crush) or prevented (section with ligation), and does not reverse at times when peripheral fibers reinnervate the periphery. We also show that 15 times more synaptic terminals in lamina II are labelled by B‐HRP 2 weeks after axotomy than in the normal. We interpret this as indicating that the sprouting fibers are making synaptic contacts with postsynaptic targets. This implies that A‐fiber terminal reorganization is a prominent and long‐lasting but not permanent feature of peripheral axotomy. We also provide evidence that this sprouting is the consequence of a combination of an atrophic loss of central synaptic terminals and the conditioning of the sensory neurons by peripheral axotomy. The sprouting of large sensory fibers into the spinal territory where postsynaptic targets usually receive only small afferent fiber input may bear on the intractable touch‐evoked pain that can follow nerve injury.

ISSN:0092-7317    

DOI:10.1002/cne.903600109

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractAxonal tracing techniques were used to study the projection from the cochlear nucleus to the superior paraolivary nucleus in guinea pigs. Different tracers were used to identify the cell types that give rise to the projections, the morphology of their axons, and the cell types that they contact in the superior paraolivary nucleus. Injections of Fluoro‐Gold or peroxidase‐labeled WGA and HRP into the superior paraolivary nucleus labeled multipolar cells and octopus cells bilaterally in the ventral cochlear nucleus, mainly on the contralateral side. Injections of PHAL into the ventral cochlear nucleus labeled two types of axons in the superior paraolivary nucleus. Thin axons branch infrequently and give rise primarily to small, en passant boutons. Thick axons have larger boutons, many of which are terminal boutons that arise from short collaterals. Thin axons appear to originate from multipolar cells, whereas thick axons probably originate from octopus cells. Both types are found bilaterally after an injection into the ventral cochlear nucleus on one side. Individual thick or thin axons may contact multiple cell types in the superior paraolivary nucleus. Individual cells in the superior paraolivary nucleus can receive convergent input from both thick and thin axons. Combined anterograde and retrograde transport of different fluorescent tracers was used to identify the projections of the cells in the superior paraolivary nucleus that receive inputs from the ventral cochlear nucleus. Cells in the superior paraolivary nucleus that projected to the ipsilateral cochlear nucleus or to the ipsilateral inferior colliculus appeared to be contacted by axons that were labeled by anterograde transport from the contralateral ventral cochlear nucleus. Thus the projections to the superior paraolivary nucleus are in a position to affect the activity in both ascending and descending auditory pathways. © 1995 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903600110

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe aim of this study was to provide quantitative descriptions of the dendritic branching patterns of pyramidal neurones in the CA1 region of the rat hippocampus. Thirteen adult cells were filled with biocytin and reconstructed by using the light microscope.The number of basal trees arising from the soma of each cell ranged from two to eight. There was wide variation in the number of terminal segments per tree. Six cells had single apical trunks, and seven had trunks that bifurcated in stratum radiatum. The number of apical oblique trees ranged from nine to 30, with each tree usually showing a lower degree of branching than basal trees. Basal and oblique trees had similar branching patterns, with the majority of branch points occurring close to the origin of the tree. Both basal and oblique terminal segments were generally much longer than intermediate segments and constituted up to 90% of the combined dendritic length of the tree. The branching pattern of the apical tuft was different, with many relatively long intermediate segments; terminal segments contributed only some 66% of the combined dendritic length of these trees. The mean total combined dendritic length for six adult cells reconstructed and measured completely was 11,900 ± 1,000 μm (standard deviation).The relative proportions of the different parts of the dendritic system, although not the total dendritic length, were correlated with the location of the soma relative, to the cell body layer. Cells with somata close to the stratum pyramidale/stratum radiatum border had more dendrites terminating in stratum radiatum and fewer in stratum oriens than cells with somata further from it. © 1995 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903600111

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY