摘要:

AbstractRecent studies have indicated that hippocampal GABAergic neurons in both the dentate gyrus and Ammon's horn contain immunoreactivity for the calcium‐binding protein parvalbumin (PARV). Although the distribution of PARV‐positive neurons has been previously described, detailed quantitative electron microscopic studies of the PARV‐positive axon terminals in the hippocampal formation are lacking. In the present study, immunocytochemical methods were used to localize PARV‐positive neurons and axon terminals to determine their similarity to GABAergic neurons. The PARV‐positive cells and axon terminals are associated closely with the pyramidal and granule cell layers. In agreement with previous studies, the morphology of PARV‐positive neurons is similar to that of GABAergic cells, including the basket cells of both the dentate gyrus and Ammon's horn. The PARV‐positive axon terminals form exclusively symmetric synapses with somata, dendrites, dendritic spines, and axon initial segments. However, these terminals represent only a portion of the total number of terminals that form symmetric synapses. Quantitative results indicate that only 32–38% of the total number of terminals forming symmetric axosomatic synapses with principal cells of the dentate gyrus and Ammon's horn are PARV positive. Together with previous findings from light microscopic double‐labeling studies, these data indicate that the PARV‐positive terminals arise from a subpopulation of GABAergic hippocampal neurons. Finally, it is important to note that the terminal plexus of PARV‐positive hippocampal axons overlaps at all postsynaptic sites with a plexus o

ISSN:0092-7317    

DOI:10.1002/cne.903000402

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThis study is the first of three reports on the detailed morphology of horseradish peroxidase injected neurons in the medial accessory olive of the cat.Intracellular, in vivo recordings of olivary cells were made and their response to mesodiencephalic stimulation was tested. In 44 units a short latency action potential could be recorded, which was very suggestive of a monosynaptic excitatory pathway. The short latency response was frequently followed by a long latency (mean 188 msec) or rebound action potential. Recordings were followed by intracellular iontophoresis of horseradish peroxidase.A total of 21 neurons, all located within the medial accessory olive were chosen for morphological analysis. Cells could be divided into two categories on the basis of their overall morphological appearance. Type I cells (n = 5) had sparsely branching dendrites that radiated away from the soma and were usually found in the caudal part of the medial accessory olive. The axon usually originated from the soma. Type II cells (n = 16) were located more rostrally. They had larger cell bodies with dendrites that ramified extensively, forming a globular structure (mean diam. 338 μUm). The axon usually originated from a first order dendrite. No recurrent axon collaterals were observed on either type I or II cells. Both cell types carried long and complex spiny appendages; however, they were most numerous on the second and higher order dendrites of type II cells. Since the soma of these cells is usually not found in the centre of its dendritic field, even if the cell is located in the center area pf the neuropil, it is suggested that the dendritic trees of up to 100 neurons may be intricately interwoven, establishing clusters with intensive intercommunication by means of dendritic gap junctions. The abundance, length and complexity of the spiny appendages suggest an important role in this process, but may also be relevant instruments in enhancing the computational capabilities of these neurons, especially in time sensitive processes.When relating the physiological and the morphological results, it was noted that both type I and type II cells could respond to mesodiencephalic stimulation and were both able to trigger a rebound action potential. No significant correlations were found between cell size and the latency of the rebound

ISSN:0092-7317    

DOI:10.1002/cne.903000403

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractIn order to describe the morphology of dendritic spines of identified neurons in the cat inferior olive together with their gamma‐aminobutyric acid (GABA) synaptic input, a technique was used combining intracellular labeling of horseradish peroxidase with postembedding gold‐immunocytochemistry. With this technique physiologically identified olivary cells were reconstructed with the light microscope, and the horseradish peroxidase reaction product and immunogold labeling were subsequently examined in serial sections at the ultrastructural level. In addition, a degenerating neuron was observed, resulting in a triple labeling in single ultrathin sections.Quantitative and three‐dimensional analysis showed that the dendritic spines were composed of long, thin stalks ending in one or more spine heads. The spines of cells located in the caudal half of the medial accessory olive (type I cells, characterized by dendrites which run away from the soma) were found to be less complex than those, of cells located rostrally in this olivary subnucleus (type II cells, characterized by dendrites which tend to turn back towards the soma). Most, if not all, of the spines of both cell types were located within glomeruli. On average, the spines within individual glomeruli originated from 6 different dendrites (with a maximum of 8). Different spines within the same glomerulus were never derived from different dendrites of the same olivary neuron, but single spines frequently gave rise to several spine heads, which could be located either within different glomeruli or inside a single glomerulus, The glomerular spine heads originating from the same spine were rarely located near one another. All spines and most of the spine heads were contacted by both GABAergic and non‐GABAergic terminals. Most of the GABAergic terminals contained pleomorphical vesicles and displayed symmetric, synapses whereas the non‐GABAergic terminals showed usually round to oval vesicles and asymmetric

ISSN:0092-7317    

DOI:10.1002/cne.903000404

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe gamma‐aminobutyric acid (GABA) synaptic input of identified axons in the cat inferior olive was studied by use of combination of intracellular labeling with horseradish peroxidase and postembedding gold‐immunocytochemistry. With this technique olivary cells were physiologically identified and light microscopically reconstructed, and the horseradish peroxidase reaction product and the immunogold labeling were subsequently simultaneously visualized for electron microscopic investigation with the use of serial ultrathin sections.The axons of cell type I (characterized by dendrites which radiate away from the cell body) originated from the soma, whereas those of type II neurons (characterized by dendritic trees which curve back towards the soma) were derived from a primary dendrite. The axons of olivary neurons stand out by the length of their axon hillock (up to 21 μm) and initial segment (up to 40 μm). The hillock forms various spiny appendages which were located within glomeruli together with dendritic spines of other olivary neurons. Axonal spines of type II neurons were more numerous and complex looking than those of type I. The axonal spines, the shaft of the axon hillock, and the transition between the hillock and initial segment were primarily innervated by GABAergic terminals (65%) but non‐GABAergic terminals (35%) were present as well. The terminals apposed to the axons of type I neurons contacted mainly the axonal shafts, whereas most of the terminals adjacent to the axons of type II neurons established synaptic contacts with the axonal spines. The initial segments were largely devoid of synaptic input. Distally, the initial segment acquired a myelin

ISSN:0092-7317    

DOI:10.1002/cne.903000405

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe present paper aims to give a morphological basis for the study of the terminal nerve system and its relation to the whole gonadotropin‐releasing hormone (GnRH) immunoreactive (ir) neuronal system. We examined the GnRH‐ir neuronal system of a tropical fish, the dwarf gourami, by using a recently developed monoclonal antibody against GnRH (LRH13) which recognizes the amino acid sequence common to all known variants of GnRH (Park and Wakabayashi,Endocrinol. Jpn.33:257–272, '86). The ganglion cells of the terminal nerve (TN‐ggl cells) in the transitional area between the olfactory bulb and the telencephalon reacted strongly with the LRH13. A distinct bundle of axons emanating from the TN‐ggl cells ran caudally through the ventral telencephalon and the preoptic area. Some of these axons entered the optic nerve and innervated the retina. The remaining axons continued caudally to enter the hypothalamus and the midbrain. A second group of GnRH‐ir cell bodies was found in the preoptic area. A distinct bundle of GnRH‐ir fibers originating from these cell bodies innervated the pituitary. This pathway is equivalent to the preoptico‐infundibular pathway of other vertebrates, and the GnRH in this pathway is presumed to function as hypophysiotrophic hormone to facilitate the release of gonadotropins from the pituitary. The distribution of GnRH‐ir fibers in the brain was extensive. Most fibers apparently originated from the TN‐ggl cells and covered various brain regions from the olfactory bulb to the spinal cord. They were especially abundant in the olfactory bulb, ventral telencephalon, preoptic area, optic tectum, and some hypothalamic areas. Thus, GnRH might function as a neuromodulator and/or neurotransmitter in these areas. The abundant GnRH‐ir fibers in the ventral telencephalon and the preoptic area might affect some aspects of sexual behavior, since these areas have been suggested to be involved in the control of sexual

ISSN:0092-7317    

DOI:10.1002/cne.903000406

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractA chordotonal organ occurring in the posterior metathorax of an atympanate moth,Actias luna(L.) (Bombycoidea: Saturniidae), appears to be homologous to the tympanal organ of the noctuoid moth. The peripheral anatomy of the metathoracic nerve branch, IIIN1b1 was examined inActias lunawith cobalt‐lysine and Janus Green B, and compared to its counterpart, IIIN1b (the tympanal branch), inFeltia heralis(Grt.) (Noctuoidea: Noctuidae). The peripheral projections of IIIN1b1 were found to be similar in both species, dividing into three branches, the second (IIIN1b1) ending as a chordotonal organ. The atympanate organ possesses three sensory cell bodies and three scolopales, and is anchored peripherally via an attachment strand to the undifferentiated membranous region underlying the hindwing alula, which corresponds to the tympanal region of the noctuoid metathorax. Extracellular recordings of the IIIN1b1 nerve inActias lunarevealed a large spontaneously active unit which fired in a regular pattern (corresponding to the noctuoid B cell) and smaller units (corresponding to the noctuoid acoustic A cells) which responded phasically to low frequency sounds (2 kHz) played at high intensities (83–96 dB, SPL) and also responded phasically to raising and lowering movements of the hindwing.We suggest that the chordotonal organ inActias lunarepresents the evolutionary prototype to the noctuoid tympanal organ, and that it acts as a proprioceptor monitoring hindwing movements. This system, in its simplicity (consisting of only a few neurons) could be a useful model for examining the changes to the nervous system (both central and peripheral) that accompanied the evolutionary development of insect tympanal org

ISSN:0092-7317    

DOI:10.1002/cne.903000407

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractUsing in vitro light microscopic autoradiography and immunocytochemistry, the distribu‐ tion of vasopressin binding sites and that of the vasopressin‐related glycopeptide are described in the brain of golden hamster (Mesocricetus auratus). Vasopressin binding sites and immunoreactive axones were observed in the suprachiasmatic nucleus, in the anterior hypothalamus/median preoptic area, in the medial preoptic nucleus, in the bed nucleus of the stria terminalis, in the habenular complex, in the thalamic paraventricular nucleus, and in the nucleus of the solitary tract.In addition we observed binding sites in regions where no immunoreactivity could be evidenced: the lateral septa1 nucleus, the central amygdaloid nucleus, the subiculum, the dentate gyrus, the anterodorsal and anteroventral thalamic nuclei, the superior colliculus, the vestibular nuclei, and in the prepositus hypoglossal nucleus.In the golden hamster, exogenous vasopressin excites single neurones located in the suprachiasmatic nucleus and induces flank‐marking behavior when microinjected into the preoptic area. Our results provide a morphological basis for similar effects exerted by endogenous vasopressin. A comparison of the present data with those previously described in the rat reveals marked species differences in the brain distribution of vasopressin and of its binding

ISSN:0092-7317    

DOI:10.1002/cne.903000408

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe sources of ipsilateral projections from the amygdala to basoventral and mediodorsal prefrontal cortices were studied with retrograde tracers (horseradish peroxidase or fluorescent dyes) in 13 rhesus monkeys. The basoventral regions injected with tracers included the orbital periallocortex and proisocortex, orbital areas 13,11, and 12, lateral area 12, and ventral area 46. The mediodorsal regions included portions of medial areas 25, 32, 14, and dorsal area 8. The above sites represent areas within two architectonic series of cortices referred to as basoventral mediodorsal on the basis of their anatomic location. Each series consists of areas that show a gradual increase in the number of layers and their delineation in a direction from the caudal orbital and medial limbic cortices, which have an incipient laminar organization, towards the eulaminated periarcuate cortices (Barbas and Pandya, J. Comp. Neurol. 286:353‐375, '89).Labeled neurons projecting to the prefrontal cortex were found in the basolateral, basomedial (also known as accessory basal), lateral, and ventral cortical nuclei, and in the anterior amygdaloid and amygdalopiriform areas. The distribution of labeled neurons differed both quantitatively and qualitatively depending on whether the injection sites were in basoventral or mediodorsal prefrontal cortices. Cases with caudal orbital injections had the most labeled neurons in the amygdala, followed by cases with injections in cortices situated medioventrally. The latter received a high proportion of their amygdaloid projections from the basomedial nucleus. The lateral amygdaloid nucleus sent a robust projection to the least architectonically differentiated orbital periallocortex, and a weaker projection to the adjoining orbital proisocortical regions, but did not appear to project to either medial proisocortical sites to the more differentiated ventrolateral or dorsolateral prefrontal cortices. In addition, there were topographical differences in the origin of projections from one amygdaloid nucleus directed to various prefrontal cortices. These differences were correlated either with the destination of the axons of afferent amygdaloid neurons to basoventral or to mediodorsal prefrontal cortices and/or with their projection to areas with varying degrees of laminar organization within the basoventral or mediodorsal sector. The clearest topography was observed for projections originating in the basolateral nucleus. The results indicate that the least architectonically differentiated basal sites situated in the caudal orbitofrontal region, followed by the comparable medial areas situated ventrally on the medial surface, received the strongest and most widespread projections from the amygdala. Medial proisocortices situated more dorsally and caudally received only a few projections from the amygdala. In addition, areas with a high degree of laminar organization (caudal areas 46 and 8) within both basoventral and mediodorsal regions received few and topographically restricted amygdaloid projection

ISSN:0092-7317    

DOI:10.1002/cne.903000409

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractTwo populations of superior olivary neurons which project to different sensory cell regions in the cochlea also give off collateral projections to the ventral cochlear nucleus (VCN) and adjacent brainstem. To determine whether these VCN projections also have different targets, they were characterized by selective retrograde amino acid transport. Retrograde transport of 3H‐d‐aspartate (D‐ASP) selectively labeled the unmyelinated fibers and neurons of the lateral olivocochlear (OC) system, including a dense collateral projection to the central VCN. Retrograde transport of 3H‐nipecotic acid (NIP) labeled the myelinated fibers and neurons of the medial OC system, including collateral projections to the peripheral VCN, subpeduncular granule cells, and nucleus Y. Medial and lateral OC efferent collaterals thus innervate different regions of the CN. Lateral system collaterals overlap extensively with Type I spiral ganglion cell afferent input. They are well positioned to play a role in modulating afferent input to the central auditory system, as is the primary projection of these efferents to the cochlea. The medial system collaterals project near the recently described afferent projections of Type I1 spiral ganglion cells. The medial system collaterals may therefore be related to the function of outer hair cells, as the medial system primary axons appear to be in the

ISSN:0092-7317    

DOI:10.1002/cne.903000410

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractIntracellular injection of Lucifer Yellow (LY) was used to study the detailed morphology of the normal, visually deprived, and light‐deprived superior colliculus projecting Type I retinal ganglion cells (RGCs) in hamsters. The soma size of the normal Type I cells ranged from 337 to 583 pm2 with a mean of 436 pm2. Two to six primary dendrites were observed in these cells. The mean dendritic field diameter was 495 km and ranged from 309 to 702 pm. The dendritic field diameter of this population of cells exhibited an eccentricity dependence. Quantitative comparisons between the normal and visually deprived or light‐deprived Type I RGCs indicated that the morphology of these three groups of cells were similar to each other in terms of the soma size, dendritic field diameter, branching pattern, and total length of the dendrites.During the normal development of cats and hamsters, several transient features, such as exuberant dendritic spines and intraretinal axonal branches, have been observed in the developing RGCs. The complete elimination of these transient features occurs at about 3 and 2 weeks after the opening of the eyes in cats and hamsters, respectively. In the present study, the hypothesis whether visual experience or light stimulation is required for the elimination of these transient features during development was examined. After studying a total of 115 mature Type I RGCs, which included cells from the normal, visually deprived, and light deprived animals, no transient feature was observed.We conclude that visual or light deprivation has no effect on the morphological develop‐ ment of superior colliculus projecting Type I RGCs in hamsters, and the elimination of the transient features on the Type I RGCs during development does not depend on visual experience or light stimul

ISSN:0092-7317    

DOI:10.1002/cne.903000411

出版商:Wiley‐Liss, Inc.    

年代:1990

数据来源: WILEY