bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology of identified interneurons in the CA1 regions of guinea pig hippocampus
Authors: Schwartzkroin Philip A. , Kunkel Dennis D. 
Published: January 2005

AbstractIdentified interneurons in the CA1 region of guinea pig hippocampus were examined using light and electron microscopic (EM) techniques. The HRP was intracellularly injected into cells, recorded in the in vitro slice preparation, which met physiological criteria for interneurons. These neurons were characterized at the light and electron microscopic level, and used as standards for identifying interneurons which had not been HRP‐labeled. Pyramidal basket cell somata were found in stratum oriens and stratum pyramidale; they were easily identifiable by their convoluted nucleus, dense endoplasmic reticulum, and numerous organelles. Aspinous dendrites reached into strata radiatum and lacunosum/moleculare, as well as ramifying within stratum oriens, where they received profuse synaptic input (primarily asymmetric synapses). Many of the asymmetric synapses degenerated following commissural lesions, suggesting that much of the input to interneurons was from extrinsic afferents. Dendrites were characterized by their spindled appearance, especially at distal sites. They showed postsynaptic degenerative changes following commissural lesions. Interneuron axons were extremely fine, with regular enlargements or “beads” which made apparent synaptic contacts primarily on pyramidal cell somata. The axon of a single, HRP‐injected interneuron made many apparent contacts on large numbers of pyramidal cells; axons arborized over distances of several hundred micra within stratum pyramidale.This study provides direct evidence that neurons, with an identified inhibitory interneuron function in hippocampus, can mediate feed‐forward as well as feed‐back (recurrent) inhibition. Interneuron output showed extreme divergence, with influence over large distances. The high density of intracellular organelles in these cells suggested high metabolic activity and demand, perhaps making these interneurons exceptionally vulnerable to trauma‐induced damage.
Neuronal death and synapse elimination in the olivocerebellar system. II. Cell counts in the inferior olive of adult X‐irradiated rats and weaver and reeler mutant mice
Authors: Shojaeian Hadi , Delhaye‐Bouchaud Nicole , Mariani Jean 
Published: January 2005

AbstractCell death in the developing rat inferior olive precedes the regression of the polyneuronal innervation of Purkinje cells by olivary axons (i.e., climbing fibers), suggesting that the involution of the redundant olivocerebellar contacts is caused by a withdrawal of supernumerary axonal collaterals rather than by degeneration of the parent cell. However, a subsequent apparent increase of the olivary population occurs, which could eventually mask a residual presynaptic cell death taking place at the same time. Therefore, cell counts were performed in the inferior olive of adult rodents in which the multiple innervation of Purkinje cells by olivary axons is maintained, with the idea that if cell death plays a role in the regression of supernumerary climbing fibers, the number of olivary cells should be higher in these animals than in their controls. The results show that the size of the cell population in the inferior olive of weaver and reeler mutant mice and rats degranulated by early postnatal x‐irradiation does not differ significantly from that of their controls. Similarly, the distribution of the cells in the four main olivary subnuclei is not modified in weaver mice and x‐irradiated rats. The present data further support the assumption that the regression of the polyneuronal innervation of Purkinje cells occurs independently of cell death in the presynaptic population.
6‐OHDA‐Induced ectopia of external granule cells in the subarachnoid space covering the cerebellum. III. Morphology and synaptic organization of ectopic cerebellar neurons: A scanning and transmission electron microscopic study
Authors: Sievers Jobst , Mangold Ulrich , Berry Martin 
Published: January 2005

AbstractThe present report describes the ultrastructure, surface morphology, and synaptic connectivity of ectopically placed cerebellar neurons after treatment of newborn rats with 100 μg 6‐hydroxydopamine (6‐OHDA), administered intracisternally. In addition to granule cells which form the majority of ectopic neurons, neurons exhibiting the ultrastructure of basket/stellate cells are found in the subarachnoid space over the cerebellum. The ectopic neurons present an almost complete spectrum of homologous efferent and afferent connections. Parallel fiber synapses are found on thorns of spiny branchlets of Purkinje cell dendrites which also have grown out into the subarachnoid space, and on the somata and dendrites of basket/stellate cells. Many ectopic parallel fibers are seen to pass into the molecular layer of the underlying cerebellar cortex through defects in the pial surface, presumably connecting with intracortical postsynaptic partners. Synapses between ectopic Purkinje cell dendrites and basket/stellate cell axons are also observed; however, the source of these axons remains uncertain. Granule cell dendrites are engaged in glomeruli with mossy fibers. Moreover, ectopic granule cell colonies are densely innervated by noradrenergic fibers. Our results show that the technique of generating ectopia of external granule cells provides an additional model for investigating influences of epigenetic factors on the development of nerve cells.
Aging in the rat medial nucleus of the trapezoid Body. II. Electron microscopy
Authors: Casey Michael A. , Feldman Martin L. 
Published: January 2005

AbstractThe medial nucleus of the trapezoid body (MTB), the largest cell group of the rat superior olivary complex, was studied ultrastructurally in five groups of rats ranging in age from 2 to 33 months. Relatively little aging pigment (lipofuscin) accumulates intraneuronally, even in rats aged 33 months. The heaviest accumulation of age pigment is in glial and perivascular cells of the MTB. In rats aged 24–33 months, there is evidence of axonal and dendritic degeneration in the MTB neuropil. Aged rats also show evidence of degeneration of nerve endings. This includes the loss of calycine axosomatic terminals synapsing with MTB principal cells. All of the ultrastructural changes observed in the MTB gradually increase in frequency with advancing age.
Ultrastructural study of cholecystokinin‐immunoreactive cells and processes in area CA1 of the rat hippocampus
Authors: Harris Kristen M. , Marshall Patricia E. , Landis Dennis M. D. 
Published: January 2005

AbstractWe used light and electron microscopic immunocytochemical methods to examine the structure of neuronal perikarya and processes containing cholecystokinin‐like immunoreactivity (CCK‐IR) in area CA1 of the rat hippocampus. The morphology of stained perikarya, their positions within all laminae, and the orientation of their dendrites indicate that CCK‐IR is located in interneurons. These cells were seen in the electron microscope to have deeply folded nuclei and to receive both symmetric and asymmetric synaptic junctions on their cell somata and dendritic shafts. Their dendrites are essentially spine‐free, but form bulges at the site of some asymmetric synaptic junctions. Axonal varicosities containing CCK‐IR make symmetric synaptic junctions with cell somata and dendritic shafts of both pyramidal and non‐pyramidal neurons. In addition, CCK‐IR varicosities form symmetric junctions with unstained non‐pyramidal neurons and with CCK‐IR cells, suggesting either recurrent innervation of one cell on itself or interaction between interneurons. The presence of CCK‐IR varicosities and synaptic junctions on pyramidal cells is in agreement with physiological data which indicate that CCK has a direct postsynaptic action. The observation of CCK‐IR varicosities forming synaptic junctions on non‐pyramidal cells suggests that CCK might also modify the response of interneurons.
The vasopressinergic innervation of the brain in normal and castrated rats
Authors: DeVries G. J. , Buijs R. M. , van Leeuwen F. W. , Caffé A. R. , Swaab D. F. 
Published: January 2005

AbstractA detailed description is given of the distribution of vasopressin‐immunoreactive structures in the brain of intact adult male rats. By application of a modified immunocytochemical procedure, vasopressin‐ immunoreactive fibers were detected in many new areas.In adult male rats which were castrated 15 weeks before death, vasopressin‐immunoreactive cell bodies had disappeared from the bed nucleus of the stria terminalis and the medial amygdaloid nucleus. No obvious changes were found in vasopressin‐immunoreactive cell bodies in other areas. Furthermore, a very strong reduction was seen in the density of vasopressin‐immunoreactive fibers in the olfactory tubercle, nucleus of the diagonal band and its immediate surroundings, ventral pallidum, basal nucleus of Meynert, lateral septum, septofimbrial nucleus, ventral hippocampal formation, amygdaloid area, pre‐ and supramammillary nucleus, supramam‐millary decussation, (inter)dorsomedial, parafascicular, and ventral aspect of paraventricular thalamic nuclei, zona incerta, lateral habenular nucleus, ventral tegmental area, substantia nigra, periventricular gray, dorsal and median raphe nucleus, and locus coeruleus. No changes were observed in other areas containing vasopressin‐immunoreactive fibers. These changes following gonadectomy were not observed in castrated rats which had been treated with testosterone.The results suggest that vasopressin projections from the bed nucleus of the stria terminalis and possibly from the medial amygdaloid nucleus require the presence of gonadal hormones for their normal appearance. This is in contrast to pathways arising from the hypothalamic vasopressin‐producing nuclei, which fail to show obvious changes following castration.
Synaptic connections between the hindwing stretch receptor and flight motor neurones in the locust revealed by double cobalt labelling for electron microscopy
Authors: Peters Brian H. , Altman Jennifer S. , Tyrer N. Mark 
Published: January 2005

AbstractSynaptic interactions between sensory and motor neurones in the locust flight system have been investigated by using intracellular labelling with cobalt and nickel for electron microscopy. Simultaneous axonal filling of two neurones with different concentrations of metal ions produces differential labelling, so that contacts between them in the central nervous system can be recognized. We have investigated the connectivity of the hindwing stretch receptor neurone (SR) with a direct hindwing depressor motor neurone (MN 127) known from physiological experiments to receive monosynaptic input from the SR, and an indirect hindwing depressor motor neurone (MN 112/1), for which no monosynaptic connection with the SR has been reported.We have found no direct synapses between the SR and MN 112/1, although some of their branches lie close together in the neuropile. We have, however, found some evidence for polysynaptic connections between them.There are many synapses of conventional dyadic morphology from both the lateral and mediolateral branches of the SR to MN 127; the medial branch was not examined. Those from the lateral branch contact the motor neurone on branches close to the neuropilar segment, while those from the mediolateral branch contact long, thin distal twigs. We estimate that there are about 600 anatomical synapses between these two neurones. Our results suggest that a large number of widely distributed anatomical synapses constitute the physiological synaptic connection between the SR and MN 127. The dyadic arrangement of these synapses provides an anatomical correlate for the physiologically established divergence of SR outputs onto interneurones and motor neurones.
A combined golgi and autoradiographic study of (3H)glycine‐accumulating amacrine cells in the cat retina
Authors: Pourcho Roberta G. , Goebel Dennis J. 
Published: January 2005

AbstractGolgi techniques were combined with electron microscopic autoradiography to identify four subpopulations of amacrine cell in the cat retina which accumulate (3H)glycine. These subpopulations include types A3, A4, A7(AII), and A8 amacrine cells. All are narrow‐field cells with dendritic spreads of less than 100 μm. Quantification of silver grains showed that each subpopulation exhibits a consistent affinity for (3H)glycine. Type A8 cells were found to have the greatest affinity with normalized grain densities of 0.88–1.0 grains/μm2 on a scale in which 1.0 represents the most heavily labeled cell. Type A4 cells were moderately labeled with grain densities ranging from 0.40 to 0.68 grains/μm2. A7(AII) and A3 amacrines were lightly labeled with grain densities of 0.33–0.35 grains/μm2 and 0.28–0.30 grains/μm2, respectively.
Development of the subretinal space in the preterm human eye: Ultrastructural and immunocytochemical studies
Authors: Johnson A. Tim , Kretzer Frank L. , Hittner Helen M. , Glazebrook Pat A. , Bridges C. D. B. , Lam Dominic M. K. 
Published: January 2005

AbstractTo investigate the development of the subretinal space in the human infant, eyes were obtained from 12 live‐born, anomaly‐free, preterm infants from 20 to 32 weeks gestation and from one 3‐month postterm infant. The retinas were studied by light microscopy, electron microscopy, and immunocytochemistry. The immunocytochemical studies utilized rabbit antiserum against purified bovine interstitial retinol binding protein (IRBP). A subretinal space containing IRBP was present in the central retina at 20 weeks and extended further into the periphery (expressed as a percentage of the distance from the optic disc to the ora serrata in the temporal hemisphere) as the retina developed. At 28 weeks, IRBP was absent only from the most peripheral 25% of the retina and reached the temporal ora serrata at 32 weeks. At 3 months postterm, IRBP immunofluorescence outlined fully developed photoreceptors, which were present from the optic disc to the ora serrata. The appearance of IRBP in the subretinal space correlated with the development of the first photoreceptor outer segment discs.
Multiaxonal horizontal cells in the retina of the tree shrew, Tupaia glis
Authors: Mariani Andrew P. 
Published: January 2005

AbstractThe retinas of most vertebrates contain two or more morphologically distinct types of horizontal cell, and usually one of these types lacks an axon. Among mammals, in which two types are observed, primates are exceptional in that both types of horizontal cell have axons. It then seemed of interest to study the horizontal cells of tree shrews (Tupaia glis), insectivores thought to be closely related to primates. Golgi impregnations of whole, flat‐preparations revealed two types of horizontal cell. Uniaxonal cells have a compact dendritic organization with clusters of terminals, and a single thin axon with short collaterals and a few terminals, located along its length. Multiaxonal cells have a relatively large dendritic tree, and arising from the tips of about four to eight dendrites of an individual cell are thin axonlike processes which terminate as profusely branched telodendritic arborizations. This identification of the multiaxonal horizontal cells in Tupaia retina is the first time any vertebrate horizontal cell has been found to possess more than a single axon. A comparison of horizonal cells in tree shrew, monkey, cat, and squirrel retinas shows a remarkable morphological diversity within this class of mammalian retinal neuron.
Anterograde axonal transport and intercellular transfer of WGA‐HRP in trigeminal‐innervated sensory receptors of rat incisive papilla
Authors: Chan Kwan Y. , Byers Margaret R. 
Published: January 2005

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 physiology.
The pretectal nucleus Lentiformis mesencephali of Rana pipiens
Authors: Montgomery Neil M. , Fite Katherine V. , Grigonis Antony M. 
Published: January 2005

AbstractThe pretectal nucleus lentiformis mesencephali (nLM) of Rana pipiens was 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, except in 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 arborize only in 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 nLM except the 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 optokinetic nystagmus.
An investigation of cholinergic circuitry in cat striate cortex using acetylcholinesterase histochemistry
Authors: Bear Mark F. , Carnes Kenneth M. , Ebner Ford F. 
Published: January 2005

AbstractThe organization of cholinergic inputs to cat striate cortex (area 17) was studied by using a histochemical stain for acetylcholinesterase (AChE). Axons were labelled in all layers of the striate cortex, with distinct plexuses occurring in layer I, lower layer III, layer IVc, and layer VI. In addition to the stained axons, a population of layer V pyramidal cells was intensely AChE‐positive.Surgical undercutting eliminated virtually all of the AChE‐positive axons in the striate cortex, thus indicating that this innervation arises entirely from an extrinsic source in the cat. To identify this source, cell groups projecting to area 17 were retrogradely labelled with horseradish peroxidase. Cell groups labelled with horseradish peroxidase that were also intensely AChE‐positive were considered as possible candidates for providing the cholinergic input to the striate cortex. These included the basal forebrain, several intralaminar nuclei, and the lateral geniculate nucleus. Kainate lesions were then made in each of these structures to assess their individual contributions to the cortical AChE pattern. Cortical AChE was depleted only after lesions of the basal forebrain, suggesting that this is the sole source of AChE‐positive axons in area 17. Because the cortically projecting cells in this region have been shown to contain choline acetyltransferase in a number of species, we postulate that the AChE‐positive fibers we describe in the cat striate cortex are in fact cholinergic.