bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of increasing ploidy on the lumbar lateral motor column and hindlimb of newly metamorphosed Xenopus laevis: A comparison of diploid and triploid siblings
Authors: Sperry David G. 
Published: January 2005

AbstractThis study was undertaken to determine how increasing ploidy in Xenopus laevis affected the size of the lumbar lateral motor column (L‐LMC) motoneuron population, the size of representative hindlimb muscles, and the relationship between these features in animals at the completion of metamorphosis. Triploids were produced by exposing fertilized diploid eggs to increased hydrostatic pressure. In the triploids, L‐LMC motoneuron number was significantly reduced and motoneuron nuclear cross‐sectional area was significantly increased. Both L‐LMC length and the total L‐LMC size (neuron number × mean nuclear size) were roughly equal in diploids and triploids. No ploidy‐related differences in fiber number were observed in two representative thigh muscles.In diploid animals, motoneuron number is significantly correlated with both muscle fiber number and with body size. The latter two variables are also significantly correlated with one another, making it possible that a feature related to muscle fiber number or one related to body size or both are significant in determining motoneuron number. In triploid animals, motoneuron number was significantly correlated with body size but not with muscle fiber number. This suggests that the feature significant in determining motoneuron number may be one related to body size rather than to muscle fiber number. If a feature related to muscle fiber number were the primary determinant of motoneuron number, one would have expected in addition similar average changes in the two variables in comparing diploids and triploids. That this was not observed provides further reason to suspect muscle fiber numbers may not be a primary determinant of motoneuron number.In both diploids and triploids, total L‐LMC size (a value combining neuron number and neuron size) was highly correlated with body size, but again, not with muscle fiber number. The average total L‐LMC size and the average body size were equal in diploids and triploids while average motoneuron number was significantly different. What this suggests is that in discussing possible mechanisms to account for correspondences between central and peripheral sizes, the relevant variable for the former may be total L‐LMC size rather than motoneuron number.
Binding pattern of alpha‐bungarotoxin on horizontal cells of a marine teleost retina
Authors: Deplano Stefania 
Published: January 2005

AbstractA conjugate of alpha‐bungarotoxin and a fluorescent marker (fluorescein isothiocyanate) has been used to localize “nicotinic” acetylcholine receptors on neurons in the outer plexiform layer of marine teleost retina. Toxin binding was confined to bipolar cell dendrites and to intermediate horizontal cells. The arrangement of labeled horizontal cells appears irregular inthe whole retina, with a peak density in the ventral and dorsal quandrants. Alpha‐bungarotoxin receptors on horizontal cells differ from those on bipolar cells and from those on dendrites in the inner plexiform layer in their sensitivity to agonists and antagonists such as d‐tubocurarine and nicotine. They consistute a different type of “nicotinic” receptor that probably has a different function.
Cell death in suboptic necrotic centers of chick embryo diencephalon and their topographic relationship with the earliest optic fiber fascicles
Authors: Navascuéeas Julio , Martíian‐Partido Gervasio , Alvarez Ignacio S. , Rodríiaguez‐Gallardo Lucíiaa 
Published: January 2005

AbstractThe structural features of suboptic necrotic centers (SONCs) in the floor of the chick embryo diencephalon were studied. These necrotic areas were observed lateral to the prospective zone of the optic chiasm through developmental stages 14 to 24. The relationship between SONCs and the earliest optic fiber fascicles also was studied in an attempt to determine the possible significance of these cell death areas in the mechanism of optic pathway development.In SONCs, healthy neuroepithelial cells contain primary lysosomes and phagocytose fragments of dead cells. Discrete regions within the cytoplasm of some cells show electron‐transparent vacuoles in contact with dense contents of ruptured lytic bodies. The cytoplasm of dying cells and dead cell fragments are notably electron dense, with numerous secondary lysosomes and electron‐transparent vacuoles. These observations are interpreted on the assumption that after autophagic processes, condensation and fragmentation take place in dying cells of the SONCs.In the ventricular lumen adjacent to the SONCs, numerous more or less spherical bodies are observed that appear to be shed from the tip of the cells constituting the SONCs. Three different types of intraventricular bodies can be distinguished: loose, moderately dense, and highly dense. The first type appears to originate from apical portions of cells that undergo autolytic processes. Moderately dense fragments are interpreted as originating from dying cells in which the cytoplasm is undergoing condensation. Finally, highly dense intraventricular bodies appear to be fragments of dead cells that are shed into the ventricular lumen.SONCs separate the prospective area of the optic chiasm from lateral regions of the diencephalic floor. Extracellular spaces are poorly developed within the wall of the SONCs, whereas the neuroepithelium of the presumptive optic chiasm and regions located rostral and caudal to SONCs show abundant and extensive extracellular spaces. These are bounded by long marginal processes of neuroepithelial cells. Sagittal sections of embryonic heads at stages 22–24 reveal optic fiber fascicles penetrating the SONCs asymmetrically, as they are found only in its caudal half. These observations suggest that the SONCs function as doorways made of compact neuroepithelium, to be traversed by the earliest optic fibers before they reach the middle zone of the floor of the diencephalon through which they travel to the contralateral optic tract within large extracellular spaces.
Distribution of glutamate‐decarboxylase‐immunoreactive neurons and synapses in the rat and monkey hippocampus: Light and electron microscopy
Authors: Babb Thomas L. , Pretorius James K. , Kupfer William R. , Brown W. Jann 
Published: January 2005

AbstractWe have studied the distribution of γ‐aminobutyric acid (GABA) neurons, axons, and synapses in the rat and monkey hippocampal formation by using gluta nate decarboxylase (GAD) immunocytochemistry together with Nissl stairs, electron microscopy, and double‐labeled retrograde transport of horseradish peroxidase. The numbers of GAD‐containing (putative GABA) neurons and their percentages compared to all Nissl‐stained neurons were calculated throughout all the various fields and strata of the mammalian hippocampus. Although their numbers are greatest in the polymorph region of the fascia dentata (FD) and in the principal cell layers stratum pyramidale (SP) and stratum granulosum (SG), GAD immunoreactive (GAD‐IR) cells are numerous in other strata that contain mostly dendrites and scattered cells. These GAD‐IR (putative GABA) neurons in dendritic regions may be involved in feedforward dendritic inhibition or may directly inhibit nearby neurons. We used a postmortem delay technique, which resulted in apparent diffusion of GAD into dendrites and axons and allowed better visualization of the extensive dendritic domain of GAD‐IR neurons. Computerized image analysis of GAD‐IR puncta indicated that putative GABA terminals were numerous on apical and basilar dendrites of all pyramidal cells but unexpectedly highest in the monkey presubiculum. In the rat, GAD‐IR neurons projected axons ipsilaterally from every region to the fascia dentata and CA1; however, commissural GAD‐IR axons to the fascia dentata arose from GAD‐IR neurons in only the contralateral fascia dentata and subiculum. Electron microscopy of GADstained hippocampus identified GAD‐IR neurons with non‐GAD‐IR (possibly excitatory) synapses and GAD‐IR terminals on somata and dendrites, 80% being the symmetric type and 20% the asymmetric type. In contrast, non‐GAD‐IR terminals were asymmetric 80% of the time.
Central trajectories of type II spiral ganglion neurons
Authors: Brown M. C. , Berglund A. M. , Kiang N. Y. S. , Ryugo D. K. 
Published: January 2005

AbstractPrevious attempts to trace the central pathways of the thin axons from type II spiral ganglion neurons have been hampered by technical difficulties such as fading of the reaction product as distance increases from the injection site (Ryugo et al.: Soc. Neurosci. Abstr. 12:779, '86; Brown: J. Comp. Neurol. 260:591–604, '87). By using small rodents (gerbils and mice), which have short auditory nerves, we have succeeded in filling the entire central axon and terminals of type II neurons after peripheral injections of horseradish peroxidase. The general course of the type II fibers within the auditory nerve and cochlear nucleus is similar to that of type I fibers except that terminals from type II neurons are often found in regions of the cochlear nucleus that have high densities of granule cells.
Prevention of optic nerve regeneration in the frog Hyla moorei transiently delays the death of some ganglion cells
Authors: Humphrey M. F. , Darby J. E. , Beazley L. D. 
Published: January 2005

AbstractWe have previously reported that a proportion of ganglion cells die during optic nerve regeneration in the adult frog Hyla moorei (Humphrey and Beazley, '85). Here we assess the effect of preventing optic nerve regeneration on this cell loss. The optic nerve was crushed unilaterally and regeneration was allowed to progress unimpeded in one experimental series but was prevented by ligating or capping the nerve in another.We estimated total cell numbers in the ganglion cell layer from cresylstained wholemounts, comparing each experimental retina with its unoperated partner. At 70–78 days postcrush, mean cell numbers had fallen by 31.5% for frogs with unimpeded regeneration (N = 9), a significantly greater reduction than the 21.5% (N = 8) loss for the impeded regeneration series (p < 0.001). Thereafter, cell numbers were stable for frogs with unimpeded regeneration. Cell death continued in the series with impeded regeneration, and losses exceeded those of frogs with unimpeded regeneration from 110 days postcrush. When regeneration was impeded, ganglion cell somas underwent an intense cell soma reaction and became arranged in rows radiating from the optic nerve head.Our findings indicate that some ganglion cells are transiently spared when regeneration of their axons is prevented. The abnormally extensive contacts formed between somas may delay ganglion cell loss. However, the eventual death of most ganglion cells shows them to be target‐independent in the long term.
Distribution of reduced‐nicotinamide‐adenine‐dinucleotide‐phosphate diaphorase‐positive cells and fibers in the cat central nervous system
Authors: Mizukawa Kiminao , Vincent Steven R. , McGeer Patrick L. , McGeer Edith G. 
Published: January 2005

AbstractPrevious histochemical studies have suggested that reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase exists in distinct subsets of neurons that neither belong to a single transmitter type nor embrace all the neurons using a single transmitter. As a step toward establishing the role of this enzyme, the distribution of NADPH‐diaphorase‐positive neurons and fibers in the cat central nervous system was mapped by using a direct histochemical method.Heavily stained NADPH‐diaphorase‐positive neurons with many prominent cell processes were observed in the cerebral cortex, white matter, caudate nucleus, putamen, nucleus accumbens, septal nucleus, amygdala, anterior, lateral and posterior hypothalamic areas, dorsolateral part of the periaqueductal gray, superior colliculus, central tegmental field (Berman) (pedunculopontine tegmental area), dorsal tegmental nucleus, nucleus coeruleus, mesencephalic and pontine reticular formation, gigantocellular and magnocellular tegmental fields, nucleus facialis, and motor nucleus of the vagus. Moderately stained neurons with two or three prominent cell processes were observed in the nucleus of the diagonal band of Broca, globus pallidus, and substantia innominata. Medium‐size, moderately stained neurons that had round large nuclei and no visible cell processes were found in the subthalamic nucleus, pontine gray, trapezoid body, and infratrigeminal, cochlear, and vestibular nuclei. Very dense NADPH‐diaphorase‐positive nerve terminal fields were seen in the olfactory tubercle, cortex, caudate nucleus, putamen, dentate gyrus, and interpeduncular nucleus. Intensely stained NADPH‐diaphorase‐positive nerve fibers were found in the stria terminalis, marginal region of the central tegmental field, dorsal tegmental nucleus, and spinal trigeminal tract as well as around the brachium conjunctivum. Although the staining of neurons and tracts was highly selective, they did not correspond to any single known neuronal or neurotransmitter type. Positive staining occurred in discrete subsets of neurons known to be associated with a variety of peptides and classical neurotransmitters. The functional significance of high NADPH diaphorase activity is unknown.
Neurons of origin and fiber trajectory of amygdalofugal projections to the medial preoptic area in syrian hamsters
Authors: Maragos William F. , Newman Sarah Winans , Lehman Michael N. , Powers J. Bradley 
Published: January 2005

AbstractThe amygdaloid neurons of origin and the trajectory of amygdaloid fibers to the medial preoptic area of the adult male Syrian hamster were identified by using horseradish peroxidase (HRP) histochemistry. After iontophoresis of HRP into the medial preoptic area, retrogradely labeled amygdaloid neurons were located in the dorsal and caudal parts of the medial amygdaloid nucleus and throughout the amygdalohippocampal area. No amygdaloid neurons were labeled after HRP applications confined to the most rostral portion of the medial preoptic area (anterior to the body of the anterior commissure). Following more caudal medial preoptic area injections (body of the anterior commissure to the suprachiasmatic nucleus) the distribution of retrogradely labeled cells in the medial amygdaloid nucleus and the amygdalohippocampal area revealed no topographic organization of the amygdalopreoptic connections. When amygdaloid neurons were labeled, the amygdalohippocampal area contained two to five times as many HRP‐filled cells as the medial amygdaloid nucleus.Retrogradely transported HRP could be followed from the medial preoptic area to the amygdala through fibers in the dorsomedial quadrant of the stria terminalis. In addition, electrolytic lesions of the stria terminalis prior to iontophoresis of HRP into the medial preoptic area prevented retrograde transport to neurons in both the dorsocaudal medial amygdaloid nucleus and the amygdalohippocampal area.These results confirm earlier observations describing the location of autoradiographically labeled efferents from the medial amygdaloid nucleus to the medial preoptic area and provide new information about the restricted region within the medial amygdaloid nucleus from which these projections arise. They also suggest that, unlike the projections from the medial amygdaloid nucleus to the bed nucleus of the stria terminalis, the efferents to the medial preoptic area travel entirely in the stria terminalis.
Immunocytochemical study of a temperature‐sensitive choline acetyltransferase mutant of Drosophila melanogaster
Authors: Ikeda Kazuo , Salvaterra Paul M. 
Published: January 2005

AbstractUsing a monoclonal antibody to choline acetyltransferase (ChAT), we have identified immunoreactive synaptic terminals in the neuropil regions of the cephalic ganglion of Drosophila melanogaster. This study demonstrates the distribution of antibody‐labeled structures within the optic lobe, and then investigates the immunoreactivity altered by mutation in two temperature‐sensitive ChAT alleles, chats−1 and chats−2.The general structure of the optic lobe was first observed by means of the silver impregnation technique. Then the presence of ChAT immunoreactivity was determined by the application of antibody [1G4] conjugated with HRP to frozen sections, followed by the 3,3′‐diamino‐benzidine tetratinct layers, which correspond to the three synaptic layers of the laminarneurons, in the medulla. Also, staining appeared in four distinct layers in the lobula. In addition, weaker staining was observed in the lamina, which corresponds to the retinula cell terminals. Somal layers were not stained.In Canton‐S (wild‐type), the three medullar layers stain distinctly at both 19°C and 30°C. In chats−1 at 19°C, the stain appeared in the same layers as that of Canton‐S, but with somewhat lower density. In chats−2 at 19°C, the density of the stain was even lower. The densities of the stain in these mutants were further decreased after exposing the flies to 30°C. The decreases were dependent on the length of exposure to the higher temperature. The decrease in stain of the specimens obtained after 24 hours exposure to 30°C was clearly recognizable in both chats−1 and chats−2. The stain was visually unrecognizable after 120 hrs incubation at 30°C in chats−1, and after 80 hrs in chats−2. The stained structures in the medulla are apparently terminals of the laminar neurons. α‐Bungarotoxin (α‐BTX) conjugated with HRP and visualized by the DAB‐H2O2 reaction was also used to stain frozen sections of wild‐type and mutant Drosophila. The three layers of α‐BTX‐HRP stained structures in the medulla overlapped with the layers revealed by 1G4. Exposure to high temperature (30°C) for up to 120 hours did not show any effect on the stain obtained by α‐BTX‐HRP in either allele.These results show that 1G4, a monoclonal antibody specific for Drosophila ChAT, can be used to identify ChAT‐containing neurons. In the temperature‐ sensitive ChAT mutant, chats, the reduced immunoreactivity paralleled the reduced ChAt activity levels which have been observed in this mutant.
Distribution of mu, delta, and kappa opiate receptor types in the forebrain and midbrain of pigeons
Authors: Reiner Anton , Brauth Steven E. , Kitt Cheryl A. , Quirion Remi 
Published: January 2005

AbstractLigands that are highly specific for the mu, delta, and kappa opiate receptor binding sites in mammalian brains have been identified and used to map the distribution of these receptor types in the brains of various mammalian species. In the present study, the selectivity and binding characteristics in the pigeon brain of three such ligands were examined by in vitro receptor binding techniques and found to be similar to those reported in previous studies on mammalian species. These ligands were then used in conjunction with autoradiographic receptor binding techniques to study the distribution of mu, delta, and kappa opiate receptor binding sites in the forebrain and midbrain of pigeons. The autoradiographic results indicated that the three opiate receptor types showed similar but not identical distributions. For example, mu, delta, and kappa receptors were all abundant within several parts of the cortical‐equivalent region of the telencephalon, particularly the hyperstriatum ventrale and the medial neostriatum. In contrast, in other parts of the cortical‐equivalent region of the avian telencephalon, such as the dorsal archistriatum and caudal neostriatum, only kappa receptors appeared to be abundant. Within the basal ganglia, all three types of opiate receptos were abundant in the striatum and low in the pallidum. Within the diencephalon, kappa and delta binding was high in the dorsal and dorsomedial thalamic nuclei, but the levels of all three receptor types were generally low in the specific sensory relay nuclei of the thalamus. Kappa binding and delta binding were high, but mu was low in the hypothalamus. Within the midbrain, all three receptor types were abundant in both the superficial and deep tectal layers, in periventricular areas, and in the tegmental dopaminergic cell groups.In many cases, the distribution of opiate receptors in the pigeon forebrain generally showed considerable overlap with the distribution of opioid peptide‐containing fiber systems (for example, in the striatal portion of the basal ganglia), but there were some clear examples of receptor‐ligand mismatch. For example, although all three receptor types are very abundant in the hyperstriatum ventrale, opioid peptide‐containing fibers are sparse in this region. Conversely, within the pallidal portion of the basal ganglia, opioid peptide‐containing fibers are abundant, but the levels of opiate receptors appear to be considerably lower than would be expected. Thus, receptorligand mismatches are not restricted to the mammalian brain, since they are a prominent feature of the organization of the brain opiate systems in pigeons. Although the precise functional significance of such mismatches will require further elucidation, it nonetheless appears likely that the endogenous opioid peptides of the avian brain act through the opiate receptors whose distribution is described in the present paper.
Shape and distribution of an unusual retinal neuron
Authors: Sandell Julie H. , Masland Richard H. 
Published: January 2005

AbstractRabbit retinas were exposed to exogenous indoleamines and fixed with mixed aldehydes. The indoleamines were accumulated by two types of amacrine cell and by an unusual cell (type 3) that branches widely in both plexiform layers. The type 3 cells were studied after immunohistochemistry, photooxidation of the fluorescent label, or injection with Lucifer Yellow. Their cell bodies are located at the scleral margin of the inner nuclear layer. The cells' arbors in the outer plexiform layer range from 800 to 1,500 μm in diameter. A descending process crosses the inner nuclear layer and branches in layer 5 of the inner plexiform layer. The arbor in the inner retina can exceed 500 μm in diameter.The distribution of type 3 cells was mapped in a series of retinal whole mounts. The number of type 3 cells ranged from 58 to 270 in different retinas. In two retinas from a single animal, however, it was virtually identical. Type 3 cells are concentrated in the region ventral to the visual streak, so that large areas of the retina are not covered by any type 3 cell. Because of their incomplete retinal coverage and variable number from animal to animal, the type 3 cells appear to be developmental anomalies. Paradoxically, their generation must be precisely controlled because of the numerical symmetry between an individual animal's two eyes.