bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology and spatial distribution of GABAergic neurons in cat primary auditory cortex (AI)
Authors: Prieto Jorge J. , Peterson Barbara A. , Winer Jeffery A. 
Published: January 2005

AbstractThis is a survey of the distribution, form, and proportion of neurons immunoreactive for gamma‐aminobutyric acid (GABA) or glutamic acid decarboxylase (GAD) in cat primary auditory cortex (AI). The cells were studied in adult animals and were classified with respect to their somatic size, shape, and laminar location, and with regard to the origins and branching pattern of their dendrites. These attributes were used to relate each of the GAD‐positive neuronal types to their counterparts in Golgi preparations.Each layer had a particular set of GABAergic cell types that is unique to it. There were 10 different GABAergic cell types in AI. Some were specific to one layer, such as the horizontal cells in layer I or the extraverted multipolar cells in layer II, while other types, such as the small and medium‐sized multipolar cells, were found in every layer.The number and proportion of GABAergic cells were determined by using postembedding immunocytochemistry. The proportion of GABAergic neurons was 24.6%. This was slightly higher than the values reported elsewhere in the neocortex. The laminer differences in density and proportion of GABAergic and non‐GABAergic neurons were also comparable (though somewhat higher) to those found in other cortical areas: thus, 94% of layer I cells were GABAergic, while the values in other layers ranged from 27% (layer V) to 16% (layer VI). Layer VI had the most heterogeneous population of GABAergic neurons.The proportion of these cells across different regions within AI was studied. Since some receptive field properties such as sharpness of tuning and aurality are distributed non‐uniformly across AI, these might be reflected by regional differences across the cerebral cortex. There were significantly more GABAergic somata in layers III and IV in the central part of AI, along the dorsoventral axis, where physiological studies report that the neurons are tuned most sharply (Schreiner and Mendelson [1990] J. Neurophysiol. 64:1442–1459). Thus, there may be a structural basis for certain aspects of local inhibitory neuronal organization. © 1994 Wiley‐Liss, Inc.
Laminar distribution and neuronal targets of GABAergic axon terminals in cat primary auditory cortex (AI)
Authors: Prieto Jorge J. , Peterson Barbara A. , Winer Jeffery A. 
Published: January 2005

AbstractThe form, density, and neuronal targets of presumptive axon terminals (puncta) that were immunoreactive for gamma‐aminobutyric acid (GABA) or its synthesizing enzyme, glutamic acid decarboxylase (GAD), were studied in cat primary auditory cortex (AI) in the light microscope. High‐resolution, plastic‐embedded material and frozen sections were used. The chief results were: (1) There was a three‐tiered numerical distribution of puncta, with the highest density in layer Ia, an intermediate number in layers Ib–IVb, and the lowest concentration in layers V and VI, respectively. (2) Each layer had a particular arrangement: layer I puncta were fine and granular (less than 1 μm), and layer V and VI puncta were mixed in size and predominantly small. (3) The form and density of puncta in every layer were distinctive. (4) Immunonegative neurons received, in general, many more axosomatic puncta than immunopositive cells, with the exception of the large multipolar (presumptive basket) cells, which invariably had many puncta in layers II–VI. (5) The number of puncta on the perikarya of GABAergic neurons was sometines related to the number of puncta in the layer, and in other instances it was independent of the layer. Thus, while layer V had a proportion of GABAergic neurons similar to layer IV, it had only a fraction of the number of puncta: perhaps the intrinsic projections of supragranular GABAergic cells are directed toward layer IV, as those of infragranular GABAergic neurons may be.Since puncta are believed to be the light microscopic correlate of synaptic terminals, they can suggest how inhibitory circuits are organized. Even within an area, the laminar puncta patterns may reflect different inhibitory arrangements. Thus, in layer I the fine, granular endings could contact preferentially the distal dendrites of pyramidal cells in deeper layers. The remoteness of such terminals from the spike initation zone contrasts with the many puncta on all pyramidal cell perikarya and the large globular endings on basket cell somata. Basket cells might receive feed‐forward disinhibition, pyramidal cells feed‐forward inhibition, and GABAergic non‐basket cells would be the target of only sparse inhibitory axosomatic input. Such arrangements imply that the actions of GABA on AI neurons are neither singular nor simple and that the architectonic locus, laminar position, and morphological identity of a particular neuron must be integrated for a more refined view of it role in cortical circuitry. © 1994 Wiley‐Liss, Inc.
Localization of nerve growth factor (NGF) and low‐affinity NGF receptors in touch domes and quantification of NGF mRNA in keratinocytes of adult rats
Authors: English Kathleen B. , Harper Sarah , Stayner Naida , Wang Zheng‐Ming , Davies Alun M. 
Published: January 2005

AbstractTouch doems are clearly delineated mechanoreceptors that are visible on the depilated skin of mammals. These structures consist of a sharply circumscribed disk of thickened epithelium surmounting a group of Merkel cells that are innervated by type I sensory neurons. These characteristic cutaneous structures provide an ideal opportunity for investigating whether the localization of nerve growth factor (NGF) in the skin related to sites of sensory axon termination. For these reasons, we have used immunocytochemistry to study the distribution of NGF and the low‐affinity NGF receptor (p75NGFR) in the touch domes of adult rat skin. Intense NGF‐like immunoreactivity was sharply restricted to keratinocytes (excluding the stratum corneum) of the thickened epidermis of the touch domes. The epidermis immediately surrounding touch domes and the epidermis of the tylotrich hair follicle associated with touch domes were immunonegative for NGF but were immunopositive for p75NGFR as werer the type I nerve endings innervating these cells. Quantitative Northern blotting revealed that the level of NGF mRNA was substantially higher in keratinocytes isolated from the stratum granulosum and stratum spinosum than in keratinocytes isolated from the stratum germinativum. These findings indicate that NGF synthesis in mature skin has a highly restricted regional distribution that is primarily associated with the innervation of a specialized touch receptor. © 1994 Wiley‐Liss, Inc.
Structure of reticulospinal axon growth cones and their cellular environment during regeneration in the lamprey spinal cord
Authors: Lurie Diana I. , Pijak Donald S. , Selzer Michael E. 
Published: January 2005

AbstractThe large larval sea lamprey is a primitive vertebrate that recovers coordinated swimming following complete spinal transection. An ultrastructural study was performed in order to determine whether morphologic features of regenerating axons and their cellular environment would provide clues to their successful regeneration compared to their mammalian counterparts. Three larvel sea lampreys were studied at 3, 4 and 11 weeks following complete spinal transection and compared with an untransected control. Müller and Mauthner cells or their giant reticulospinal axons (GRAs) were impaled and injected with horseradish peroxidase (HRP). Alternating thick and thin sections were collected for light and electron microscopy. A total of 9 neurites were examined.At all times, growth cones of GRAs differed from those of cultured mammalian neurons in being packed with neurofilaments and in lacking long filopodia, suggesting possible differences in the mechanisms of axon outgrowth. Morphometric analysis suggested that GRA growth cones contact glial fibers disproportionately compared to the representation of glial surface membranes in the immediate environment of these growth cones. No differences were found between glial cells in regenerating spinal cords and those of untransectred control animals with regard to the size of the cell body and nucleus and the packing density of their intermediate filaments. Glial fibers in control animals and glial fibers located far from a transection were oriented transversely. Glial cells adjacent to the transection site sent thickened, longitudinally oriented processes into the blood clot at the transection site. These longitudinal glial processes preceded the regenerating axons. Desmosomes were observed on glia adjacent to the lesion but were scarce in the lesion during the first four weeks post‐transection. These findings suggest that longitudinally oriented glial fibers may serve as a bridge along which axons can regenerate across the lesion. The presence of desmosomes might prevent migration of astrocytes near the transection, thus stabilizing the glial bridge. © 1994 Wiley‐Liss, Inc.
Redistribution of insoluble interphotoreceptor matrix components during photoreceptor differentiation in the mouse retina
Authors: Mieziewska Kristina , Szél Agoston , van Veen Theo , Aguirre Gustavo D. , Philp Nancy 
Published: January 2005

AbstractThe development of the nervous‐system is largely influenced by the extracellular matrix (ECM). In the neural retina, the photoreceptors are surrounded by a unique ECM, the interphotoreceptor matrix (IPM). The IPM plays a central and possibly crucial role in the development, maintenance and specific function of the photoreceptors. Therefore, the characterization of IPM components is necessary to understand the mechanisms regulating photoreceptor differentiation.The IPM in the mouse retina was examined during photoreceptor morphogenesis with the monoclonal antibody (MAb) F22, which recognizes a 250 kDa component of the interphotoreceptor matrix. The binding pattern of MAb F22 revealed a striking redistribution in the expression of the 250 kDa F22 antigen in late stage of postnatal photoreceptor differentiation in the mouse retina.The F22 staining was detectable in the IPM around the inner segments on the third postnatal day (P3). The MAb F22 initially labeled the region around inner segments, but as the outer segments elongated, the F22 distribution became concentrated to the matrix around the rod and cone outer segments until P16–17. At P17, the F22 label around rods began to disappear, while the label around cones became more defined. The shift in label distribution was largely completed by P20. Residual rod‐associated label disappeared within a few days. In the adult animal, the F22 antibody labeled the cone‐associated matrix only, and this labeling pattern remained stationary. The change in the distribution of MAb F22 demonstrated by immunolabeling was not accompanied by changes in the size of the molecule; F22 antigen isolated from the IPM of P13–15, and from adult IPM migrated with the same molecular weight on SDS gels.The distribution of MAb F22 was compared to that of chondroitin sulfate proteoglycans which are abundant in the IPM. The labeling patterns of MAbs CS‐56, C6‐S and C4‐S were distinct from that of MAb F22. A general decrease of the label intensity was seen with two chondroitin sulfate MAbs (CS‐56 and C4‐S) between 16 days and 4 months, but a total loss of rod‐associated label was not observed. All three chondroitin sulfate MAbs labeled the retina at embryonic day (E) 11.5–13.5, a time of outgrowth of ganglion cell axons, but the F22 antigen was not detected in the retina at this stage of development. The results demonstrate that the F22 and the chondroitin sulfate antibodies are recognizing different molecules that have distinct roles in retinal morphogenesis. The expression of the F22 antigen was temporally correlated with photoreceptor outer segment differentiation. The redistribution of F22 label at P17–20 occurred at the end of the developmental period and suggests that the F22 antigen could have different roles, both in photoreceptor differentiation, and in the mature retina. © Wiley‐Liss, Inc.
Synaptic terminal coverage of primate triceps surae motoneurons
Authors: Starr Kathy A. , Wolpaw Jonathan R. 
Published: January 2005

AbstractThis study examined the synaptic terminal coverage of primate triceps surae (TS) motoneurons at the electron microscopic level. In three male pigtail macaques, motoneurons were labeled by retrograde transport of cholera toxin‐horseradish peroxidase that was injected into TS muscles bilaterally and visualized with tetramethylbenzidine stabilized with diamino‐benzidine. Somatic, proximal dendritic, and distal dendritic synaptic terminals were classified by standard criteria and measured. Overall and type‐specific synaptic terminal coverages and frequencies were determined.Labeled cells were located in caudal L5 to rostral S1 ventral horn and ranged from 40 to 74 μm in diameter (average, 54 μm). The range and unimodal distribution of diameters, the label used, and the presence of C terminals on almost all cells indicated that the 15 cell bodies and associated proximal dendrites analyzed here probably belonged to α‐motoneurons.Synaptic terminals covered 39% of the cell body membrane, 60% of the proximal dendritic membrane, and 40% of the distal dendritic membrane. At each of these three sites, F terminals (flattened or pleomorphic vesicles, usually symmetric active zones, average contact length 1.6 μm) were most common, averaging 52%, 56%, and 58% of total coverage and 56%, 57%, and 58% of total number on cell bodies, proximal dendrites, and distal dendrites respectively. S terminals (round vesicles, usually asymmetric active zones, average contact length 1.3 μm) averaged 24%, 29%, and 33% of coverage and 33%, 35%, and 36% of number at these three sites, respectively. Thus, S terminals were slightly more prominent relative to F terminals on distal dendrites, than on cell bodies. C terminals (spherical vesicles, subsynaptic cisterns associated with rough endoplasmic reticulum, average contact length 3.5 μm) constituted 24% and 11% of total terminal coverage on cell bodies and proximal dendrites, respectively, and averaged 11% and 6% of terminal number at these two locations. M terminals (spherical vesicles, postsynaptic Taxi bodies, some with presynaptic terminals, average contact length 2.7 μm) were absent on cell bodies and averaged 3% and 7% of total coverage and 2% and 5% of terminals on proximal and distal dendrites, respectively. Except for M terminals, which tended to be smaller distally, terminal contact length was not correlated with location. Total and type‐specific coverages and frequencies were not correlated with cell body diameter.Primate TS motoneurons are similar to cat TS motoneurons in synaptic terminal morphology, frequency, and distribution. However, primate terminals appear to be smaller, so that the fraction of menitrane covered by them is lower. © 1994 Wiley‐Liss, Inc.
Changes in nerve growth factor immunoreactivity following entorhinal cortex lesions: Possible molecular mechanism regulating cholinergic sprouting
Authors: Conner J. M. , Fass‐Holmes B. , Varon S. 
Published: January 2005

AbstractTo assess the possible role of trophic factors in lesion‐induced plasticity, we have used a sensitive immunohistochemical technique to evaluate changes in nerve growth factor (NGF) staining in the hippocampal formation 3, 8, 16, and 30 days following entorhinal cortex lesions. Our results indicate that a band of NGF immunoreactivity appears in the outer molecular layer of the ipsilateral dentate gyrus following entorhinal ablation. The distribution of the NGF‐immunoreactive band exactly coincides with the distribution of sprouting cholinergic terminals revealed by acetylcholinesterase histochemistry or NGF‐receptor immunostaining. Increased NGF‐immunoreactivity is detectable at 3 days postlesion, is most intense at 8 days, and decreases to near control levels by 30 days. Lesion‐induced increases in NGF immunostaining also occur in animals in which septohippocampal fibers had been removed by prior destruction of the fimbria‐fornix. Increases in NGF‐immunoreactivity, however, are substantially reduced in animals receiving intraventricular injections of colchicine, which presumably blocks NGF release. These results indicate that (1) increases in NGF immunostaining, which occur following entorhinal lesions, precede any changes in cholinergic sprouting parameters and are greatest during the period of maximal cholinergic sprouting; (2) increased NGF‐immunoreactivity is not due to NGF binding by septohippocampal fibers; and (3) increased NGF‐immunoreactivity appears to depend on the release of NGF by neurons that produce it. We hypothesize that, following entorhinal lesions, NGF immunostaining within the hippocampal formation may represent NGF “anchored” within the tissue and that NGF accumulation by such a mechanism may direct the sprouting response of NGF‐sensitive cholinergic neurons. © 1994 Wiley‐Liss, Inc.
Distribution of synapses on two ascending interneurones carrying frequency‐specific information in the auditory system of the cricket: Evidence for gabaergic inputs
Authors: Hardt M. , Watson A. H. D. 
Published: January 2005

AbstractTwo identified cricket: auditory interneurones, AN1 and AN2, were intracellularly labelled with horseradish peroxidase following physiological characterisation. The neurones, which have some structural similarities, have their somata in the prothoracic ganglion and axons that project to the brain. Although both carry auditory information, they have different response properties and participate in different types of phonotactic behaviour. Ultrathin sections from selected regions of their Prothoracic arborisations were examined in the electron microscope after postembbdding immunostaining for the inhibitory transmitter GABA. In the prothoracic ganglion AN1 branches only in the medial ventral association centre (mVAC) contralateral to the soma, and receives only input synapses. Twenty‐seven percent of these were made by processes ‐immunoreactive for GABA. AN2 branches not only in mVAC on both sides of the ganglion but also in several other areas. It makes output synapses from large diameter neurites in mVAC on both sides of the ganglion as well as from neurites in more posterior regions of the neuropile. Most input synapses are received onto branches in the contralateral mVAC where about 19% were made from GABA‐immunoreactive processes. © 1994 Wiley‐Liss, Inc.
Early development of the somatotopic map and barrel patterning in rat somatosensory cortex
Authors: Schlaggar Bradley L. , O'Leary Dennis D. M. 
Published: January 2005

AbstractSeveral lines of evidence implicate a crucial role for thalamic afferents from the ventroposterior nucleus (VP) in the development of barrels and their characteristic pattern in the primary somatosensory cortex (Sl) of rodents. We sought to determine the stage in development when VP thalamocortical afferents are first distributed in a periphery‐related pattern and the sequence of events that culminate in a mature pattern. Using acetylcholinesterase (AChE) histochemistry, an early marker for VP thalamocortical afferents, and the anterograde axon tracer DiI, we show that VP thalamocortical afferents become distributed into a peripheryrelated pattern earlier than was previously reported, including their parcellation into a barrel‐related pattern that mirrors the distribution of sensory hairs on the face. The earliest periphery‐related patterning observed is transiently present in the deep cortical layers prior to the emergence of layer 4, the layer in which barrels later develop. AChE histochemistry reveals a clear sequence of maturation of the barrel pattern in the distribution of VP afferents: An initially patternless distribution of AChE‐reactive afferents is followed by their distribution in a nascent trigeminal representation, from which rows subsequently emerge; barrel‐related clusters of afferents then emerge from the rows. This process begins before birth, and the transition from row‐related to barrel‐related distributions of VP afferents is evident during the first postnatal day (P0). This demonstration of a periphery‐related pattern in developing rat S1 precedes by about 2 days that revealed by any other marker reported to delineate barrels. These findings confirm that VP thalamocortical afferents are the first barrel component to have a periphery‐related pattern and support the hypothesis that thalamocortical afferents provide to immature S1 the patterning information that initiates the formation of barrels and their characteristic array. Furthermore because these findings show an earlier onset for barrel formation than was previously realized, they necessitate a reevaluation of conclusions drawn from experiments examining, developmental plasticity in barrel patterning. © 1994 Wiley‐Liss, Inc.
Cytoarchitecture of the medial geniculate body in the mustached bat (Pteronotus parnellii)
Authors: Winer Jeffery A. , Wenstrup Jefferey J. 
Published: January 2005

AbstractThe cytoarchitectonic organization of the medial geniculate body and adjoining thalamic nuclei was analyzed in the mustached bat (Pteronotus parnellii). These subdivisions provide a reference for structural, physiological, conncetional, and nurochemical work. Most nuclei recognized in other mammals exist in the mustached bat, although the relative volume of the three divisions was species specific. The ventral division contains medium‐sized neurons and a few smaller cells and is well developed. Neurons in the lateral part lie in regularly aligned rows corresponding to the laminae in Golgi material; in the medial part, these laminae are obscured by fibers. The dorsal dividion has at least four nuclei, each with a unique cytoarchitecture and myeloarchitectonic organization. The suprageniculate nucleus is prominent and has many large radiate neurons. Cells in the superficial dorsal nucleus have weakly laminated dendrites, while dorsal nucleus neurons have spherical dendritic fields. There is a wide range of neuropil patterns within the dorsal division. The suprageniculate nucleus has thick myelinated axons, while the fibers in the superficial and dorsal nuclei are much thinner. The rostral pole nucleus becomes prominent in the anterior one‐half of the auditory thalamus; its architectonic affiliation is equivocal, and connectional and immunocytochemical studies suggest that it may belong to the dorsal division. The medial division is one nucleus with many types of neurons, and it has coarse axons without laminar orientation. It is the smallest of the divisions and is present throughout the medial geniculate complex, except at the caudal tip and at the rostral pole.Many features of medial geniculate body organization evident in other mammals are recognized in the mustached bat. These include a prominent ventral division, some of whose neurons have a laminar organization, and a comparatively small medial division that is devoid of fibrodendritic laminae. Other features, such as the presence of a large rostral pole nucleus, whose homologue in other species is uncertain, or the sparse number or small cells that may participate in local circuits, set it apart from carnivores and primates and suggest that there are species specific patterns of medial geniculate body organization. © 1994 Wiley‐Liss, Inc.