bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postnatal development of 3H‐GABA‐ accumulating cells in rabbit retina
Authors: Redburn Dianna A. , Madtes Paul 
Published: January 2005

AbstractLight and electron microscopic autoradiography demonstrates that 3H‐GABA is accumulated by horizontal cells in neonatal rabbit retina but not in the adult. A specific population of horizontal cells appears to be mature at birth and they avidly accumulate 3H‐GABA during a 15‐minute incubation period in vitro. Uptake into horizontal cells is not observed after the fifth postnatal day; 3H‐GABA‐accumulating horizontal cell bodies and their processes are the first identifiable components that clearly mark the future location of the outer plexiform layer at birth and as such, may be considered pioneering elements. Our observations raise the interesting possibility that the pioneering horizontal cell may provide structural and/or chemical factors necessary for the subsequent development of the outer plexiform layer of the retina.Labeling patterns of other retinal cells also show varying degrees of change during development. (1) A population of amacrine cells accumulate 3H‐GABA at birth. These cells show little change in their morphological or 3H‐GABA uptake properties from birth to adulthood. (2) Müller cells show weak accumulation of 3H‐GABA at birth. Subsequent to this time, labeling of Müller cells is significantly more robust, resulting in Müller cell domination of retinal autoradiographic patterns in more mature retinas. (3) Every cell body in the ganglion cell layer accumulates 3H‐GABA at birth. The number of labeled cells declines during postnatal development, resulting in a very limited adult population. We conclude that the ability of retinal cells to accumulate 3H‐GABA does not remain constant during postnatal development; rather each cell population displays a unique maturation sequence that results in a dramatic developmental shift in the number and types of GABA‐accumulating cells present in the retina.
Neurogenesis in reptilian cortical structures: 3H‐thymidine autoradiographic analysis
Authors: Goffinet A. M. , Daumerie Ch. , Langerwerf B. , Pieau C. 
Published: January 2005

AbstractHistogenesis was studied in forebrain cortical areas of two reptiles, Emys orbicularis and Lacerta trilineata, by using tritiated thymidine autoradiography. Four areas were considered: the dorsomedial, the general (dorsal), and the lateral cortices, and the dorsal ventricular ridge (DVR). The bulk of neurogenesis in these four pallial fields proceeds within a short period of 8‐9 days, between developmental stages 15 and 18 in Emys and stages 32‐34 in Lacerta. Lateral‐to‐medial as well as anterior‐to‐posterior tangential gradients of histogenesis are present in both species. Radial neurogenetic gradients are directed from outside to inside, except in the medial cortex of lizards, where no radial gradient is seen. This pattern of histogenesis in the cortex of turtles and lizards is comparable to that in mammals in terms of timing and tangential, areal variations. It might represent a “common denominator” of cortical histogenesis. However, in contrast to the mammalian cortex, which develops according to an inside to outside, “inverted” pattern, radial neurogenesis in the cortex of turtles and lizards follows an outside‐to‐inside gradient. These observations suggest that the inside‐out gradient of cortical neurogenesis has been acquired during evolution of the synapsid radiation from stem reptiles to mammals, and that it may be related to the development of radial cortical architectonics.
Selective cytochemical demonstration of glycoconjugate‐containing terminal N‐acetylgalactosamine on some brain neurons
Authors: Nakagawa Fukuo , Schulte Bradley A. , Spicer Samuel S. 
Published: January 2005

AbstractParaffin embedded sections of rat, mouse, dog, and human brain were stained with a battery of lectin‐horseradish perioxidase conjugates to localize and characterize glycoconjugates. In the rat and mouse cerebral cortex, a subpopulation of nonpyramidal neurons stained selectively with three lectins with specific affinity for terminal N‐acetylgalactosamine (GalNAc). These and only these lectins stained the surface of the cell body, dendritic shafts, and proximal parts of the dendritic arborization. Most reactive, nonpyramidal neurons revealed a multipolar dendritic pattern, but some possibly belonged to the bitufted and bipolar types of neuron. The GalNAc‐containing neurons appeared widely distributed in layers II–VI with relatively greater abundance in layers IV and V. In the cortex of rats and mice the stained neurons occurred in moderate numbers in the frontal, frontoparietal, striate, retrosplenial, and entorhinal regions, but were less numerous in the hippocampal gyrus, dentate gyrus, and olfactory area. Other neurons in the basal ganglia and brain stem stained weakly for GalNAc. Examination of the frontal cortex of human and canine brains showed a similar distribution of nonpyramidal neurons with affinity for GalNAc‐binding lectins. At high magnification, the surface staining of neurons in the cerebral cortex, deep cerebellar nucleus, and other sites appeared periodic rather than continuous. The periodic character of the neuronal surface staining suggested a location for the reactive glycoconjugate in or between the synapses. The GalNAc‐containing glycoconjugate occurred in a selected cell type, failed to bind the other lectin conjugates, and differed from biochemically detected glycoconjugates. It is, therefore, considered a newly recognized entity of possible physiologic significance for a population of cortical neurons.
Neurotensinlike immunoreactive neurons in the hedgehog (Erinaceus europaeus) and the sheep (Ovis aries) central nervous system
Authors: Papadopoulos G. C. , Karamanlidis A. N. , Antonopoulos J. , Dinopoulos A. 
Published: January 2005

AbstractNeurotensin‐containing neurons in the hedgehog and sheep central nervous system were studied immunohistochemically. In both species, mapping of neurotensin neurons was achieved only after pretreatment with colchicine injected intracerebroventricularly 2 days prior to perfusion. Bipolar or multipolar neurotensin neurons, 10–30 μm in diameter, were observed in the following regions of the central nervous system of both species: medial amygdaloid nucleus, lateral septal nucleus, interstitial nucleus of the stria terminals, caudate nucleus, preoptic area, and hypothalamus. On the contrary, while immunoreactive neurons were found in the central amygdaloid nucleus, nucleus accumbens, nucleus of the diagonal band, subthalamus, superior central nucleus, dorsal raphe nucleus, central gray substance of the pons, and dorsal horn of the spinal cord of the hedgehog, respective regions of the sheep appeared to be devoid of immunoreactive perikarya. Also, in some regions, namely the hippocampal formation, the central gray substance of the midbrain, the locus coeruleus, and the nucleus of the solitary tract, neurotensin neurons were found exclusively in the latter species.The existence of these differences in the distribution pattern of neurotensin‐immunoreactive neurons between the two species as well as between them and others already examined is briefly discussed.
Stellate cell development in the frog cerebellum during spontaneous and thyroxin‐induced metamorphosis
Authors: Hauser Kurt F. , Uray Nándor J. , Gona Amos G. 
Published: January 2005

AbstractStellate cell development was studied in the bullfrog cerebellum during spontaneous and thyroxin‐induced metamorphosis using the Golgi‐Kopsch method and electron microscopy. Cells that possessed axosomatic synapses and resembled stellate cells were present even in the incipient molecular layer of the cerebellum in the premetamorphic tadpole. These cells may have originated from the early, transient wave of external granule cells that have been reported in the cerebellum of premetamorphic tadpoles in the first 6 months of development, and may constitute the variant population of stellate cells that are present later during development or the degenerating cells that have been observed during metamorphosis as scattered dying cells in the molecular layer.Typical stellate cells, whose development resembled the genesis and differentiation of stellate cells in birds and mammals, were initially observed at the outer border of the molecular layer that is adjacent to the external granular layer during the onset of metamorphosis. These stellate cells were bipolar with processes extending in a plane perpendicular to elongating parallel fibers, and with progressive development, became multipolar with dendrites oriented in various directions with respect to the pia. Stellate cell axons innervate the dendrites and somata of Purkinje cells and other stellate cells, and can be categorized into two types: (1) axons with extensive branching near the soma of origin, and (2) long axons with few branches that occasionally terminate in the Purkinje cell layer. Atypical neurons that did not resemble typical stellate cells were also present in the molecular layer; these might be classified as a stellate cell variant.The generation and differentiation of stellate cells can be‐induced 1 to 2 years prematurely by administering thyroid hormone to premetamorphic tadpoles. Like most events of cerebellar histogenesis in the frog, stellate cell development also appears to be largely a thyroid‐dependent phenomenon.
Rostrocaudal differences in dendritic growth and synaptogenesis in rat sympathetic chain ganglia
Authors: Snider William D. 
Published: January 2005

AbstractVertebrate embryos show a rostral to caudal gradient of morphogenesis. I have investigated the effect of this developmental gradient on neuronal maturation and synapse formation by comparing the development of rostral and caudal sympathetic chain ganglia in the rat. In young adults the superior cervical and lumbar ganglia are almost identical in terms of neuronal morphology and quantitative aspects of innervation. In neonates, however, substantial rostrocaudal differences are apparent in dendritic complexity, number of axons innervating ganglion cells, and synaptic density. There is an associated delay in ganglion cell‐target interactions in the lumbar region.My results show that rostrocaudal position is significantly correlated with the time course of dendritic growth and synaptogenesis and suggest that ganglion cell‐target interactions may be important in these developmental processes. This difference in developmental rate, however, does not lead to differences in neuronal morphology or synaptic density between rostral and caudal ganglia in maturity.
The projections from striate cortex (V1) to areas V2 and V3 in the macaque monkey: Asymmetries, areal boundaries, and patchy connections
Authors: Van Essen D. C. , Newsome W. T. , Maunsell J. H. R. , Bixby J. L. 
Published: January 2005

AbstractThe organization of projections from V1 to areas V2 and V3 in the macaque monkey was studied with a combination of anatomical tecniques, including lesions and tracer injections made in different portions of V1 and V2 in 20 experimental hemispheres. Our results indicate that dorsal V1 (representing the inferior contralateral visual quadrant) consistently projects in topographically organized fashion to V3 in the lunate and parietooccipital sulci as well as to the middle temporal area (MT) and dorsal V2. In contrast, ventral V1 (representing the superior contralateral quadrant) projects only to MT and ventral V2. A corresponding dorsoventral asymmetry in myeloarchitecture supports the idea that V3 is an area that is restricted to dorsal extrastriate cortex and lacks a complete representation of the visual field. The average surface area of myeloarchitectonically identified V3 was 89 mm2. Additional information was obtained concerning the laminar distribution of connections from V1 to V2 and V3, the patchiness of these projections, and the consistency of projections to other extrastriate areas, including V4 and V3A.
Morphological evidence for the existence of multiple neuronal classes in the cat lateral superior olivary nucleus
Authors: Helfert Robert H. , Schwartz Ilsa R. 
Published: January 2005

AbstractThis study characterizes morphologically the neurons residing within the matrix of the cat lateral superior olive (LSO), excluding the hili and myelinated axon envelope. Several light microscopic techniques including Golgi impregnations, Nissl stains, and acetylcholinesterase histochemistry were used, as well as electron microscopy. Five distinct classes of neurons have been identified: principal neurons, multiplanar neurons, marginal neurons, small neurons, and class 5 neurons. These neuronal classes differ in regard to their size and shape, dendritic organization, perikaryal synaptic density, and their relative numbers.Principal neurons compose approximately three‐quarters of the LSO neurons. They are multipolar and uniplanar in their dendritic arborization, radiating from the hili in rostrocaudal planes perpendicular to the curvatures of the LSO. In transverse sections the principal cell perikarya are fusiform and bipolar, with mean dimensions of 23 × 11 μm. More than 60% of the surface of these cells is contacted by synaptic terminals. Multiplanar neurons (averaging 23 × 19 μm) compose only 11% of the LSO neuronal population. Their dendritic arborization is not restricted to any particular plane, and their somal surface receives synaptic contacts similar, in number and type, to principal cells. Marginal neurons, although they are similar to principal neurons in shape and dendritic arborization, differ in that they are generally smaller (averaging 20 × 10.5 μm). They also possess fewer axosomatic synaptic contacts (− 33%), are oriented perpendicularly to principal neurons, are limited in distribution to the contours of the LSO immediately beneath the myelinated axon envelope, and constitute only 4% of the neuronal population. Small neurons (mean dimensions = 9 × 8 μm) compose 8% of the LSO neurons. They possess a multiplanar array of primary dendrites and have nuclei with multiple deep infoldings. Small neurons have the fewest axosomatic synaptic contacts of all classes of LSO neurons (−10%). Additionally, there are neurons that are similar to principal neurons, but receive fewer axosomatic contacts (− 33%). These cells have been tentatively identified as class 5 neurons until more information on this type allcws for the assignment of a more descriptive name. A number of acetyleholinesterase‐positive neurons are also found within the LSO, whose relationship to the other classes of neurons is presently unresolved. Possible functions of the multiple neuronal types are discussed.
Relationship of ocular pigmentation to the boundaries of dorsal and ventral retina in a nonmammalian vertebrate
Authors: Springer Alan D. , Mednick Adam S. 
Published: January 2005

AbstractThe goldfish eye and retina are partitioned traditionally into dorsal and ventral sectors by a horizontal meridian that passes through the optic disc and is perpendicular to a vertical meridian that extends from the remnant of the choroid fissure through the optic disc. Axons of retinal ganglion cells (RGCs) situated above the horizontal meridian are thought to reach the optic tectum via the ventrolateral optic tract and axons of RGCs situated below the horizontal meridian are thought to reach the optic tectum via the dorsomedial optic tract. When cobaltous‐lysine was applied to small temporal retinal slits that were centered on the traditional horizontal meridian, filled fibers were found in the dorsomedial, but not in the ventrolateral, optic tract (Springer and Mednick, '83). Since cobalt‐filled axons should have been found in both optic tracts, the traditional horizontal meridian does not indicate the actual boundary between dorsal and ventral retina. We report here that the goldfish iris contains nasal and temporal pigmentation lines (darts) that are each located approximately 21° above the traditional horizontal retinal meridian. Cobalt applied to retinal slits located just above the darts filled RGC axons in the ventrolateral optic tract and cobalt applied to retinal slits just below the, darts filled RGC axons in the dorsomedial optic tract. Converging evidence for the reliability of the darts as indicators of the boundary between dorsal and ventral retina was obtained by applying cobalt to severed RGC axons along the dorsomedial edge of the tectum. Cobaltfilled RGCs were found below the nasal dart. The irideal darts may be useful for standardizing electrophysiological retinotectal maps across subjects and laboratories. They will also be useful for elucidating the different trajectories of dorsal and ventral RGC axons, as well as their transformations within the visual pathways.
Synaptic organization of the cone horizontal cells in the catfish retina
Authors: Sakai Hiroko M. , Naka Ken‐Ichi 
Published: January 2005

AbstractHorizontal cells of the vertebrate retina are known to contribute to the formation of the receptive fields surrounds photoreceptor and biopolar cells. However, few synapses have bee describe anatomically that might mediate these interactions. We have observed in the catfish retina that cone horizontal cell perikarya and dentrites make‐conventional chemical synapses onto photoreceptor terminal telodendria and, onto bipolar cell dendrites, while horizontal cell axon terminals make chemical synapses onto the perikarya and processes of amacrine cells. The synapses are characterized by clusters of round vesicles aggregated close to the site of contact, as well as by electron‐dense material associated with both pre‐ and postsynaptic membranes. The three kinds of synapses observed anatomically correspond to the synaptic pathways involving cone horizontal cells that have been suggested by the physiology of these cells.
A quantitative morphological study of interstrain variation in the developing rat optic nerve
Authors: Hunter A. , Bedi K. S. 
Published: January 2005

AbstractGroups of pigmented (Black and White Hooded Lister) and albino (Sprague Dawley) rats were killed at 7, 15, and 25 postnatal days of age. Their optic nerves were embedded in resin suitable for both light and electron microscopy. Quantitative stereological procedures were used to estimate total fibre number and the degree of myelination in the optic nerves at the various ages.At 7 days of age, both albino and pigmented rats had about 220,000 optic nerve fibres. By 15 days, both strains showed a reduction of some 30,000 fibres. This fibre loss continued in both strains after 15 days of age, but more rapidly in the pigmented strain. At 25 days of age, pigmented rats had 72,371 ± 7,244 fibres, whilst albino rats had 102,681 ± 4,138 fibres (P <01). More than 99.5% of optic nerve axons in both strains were unmyelifiated at 7 days of age. By 25 days of age about 90% of all remaining fibres were myelinated in both strains.The mean diameter of the myelinated axons was estimated to be between 0.59 and 0.65 μm in all animals, there being no significant age or strain differences.In contrast, the mean diameter of nonmyelinated axons increased significantly with age. This increase was greater for albino than pigmented rats, such that by 25 days of age the respective values were 0.49 μm and 0.42 μm (P < .05).
Origin of mammalian thalamocortical projections. I. Telencephalic projections of the medial geniculate body in the opossum (Didelphis virginiana)
Authors: Kudo Motoi , Glendenning K. K. , Frost Shawn B. , Masterton R. B. 
Published: January 2005

AbstractTelencephalic projections from the medial geniculate nucleus (MG) in opossum were traced with tritiated leucine autoradiography and by horseradish peroxidase and fluorescent dye retrograde labeling techniques. The results show that the opossum's MG contains two separate populations of neurons‐one in the anterior two‐thirds of MG projecting to auditory neocortex, the other occupying the entire caudal one‐third of MG and projecting mostly to lateral amygdala and putamen.Because the subcortical projection of the MG in opossum is larger than that seen in any other mammal to date, it is reminiscent of the subcortical projections off the MG in reptiles and birds. Furthermore, when the subcortical projections of the MG in reptiles and opossums are compared with % similar‐subcortical projections of the MG in rats, cats, and monkeys, the proportion of the MG neurons projecting to subcortical structures is seen to be inversely related to the recency of each‐Animal's common ancestry with primates. The possibility that the subcortical projection of the MG in mammals is homologous with that seen in reptiles or birds implies that it might be a dwindling vestige of the projection present in the common ancestry of reptiles and mammals.
Optic tectum of the eastern garter snake, Thamnophis sirtalis. IV. Morphology of afferents from the retina
Authors: Dacey Dennis M. , Ulinski Philip S. 
Published: January 2005

AbstractThe morphology of single retinal terminals in the optic tectum of the eastern garter snake was demonstrated by orthograde filling from extracellular injections of horseradish peroxidase (HRP) into the optic tract. HRP‐filled terminals share a characteristic shape and structure. Their parent axons course caudally in the stratum opticum within fascicles of 200‐300 fibers of varying diameters. Single axons exit a fascicle and course into either the stratum fibrosum et griseum superficiale, ventrally, or the stratum zonale, dorsally, where they bifurcate successively two or three times into preterminal branches. Each preterminal branch gives rise to many thin, terminal branchlets laden with boutons. The arbors are ellipsoidal with their long axes oriented mediolaterally and their short axes oriented rostrocaudally. Arbors vary in their overall size (from 45 to 150 μm), in the diameters of their parent axons (from less than 0.5 to 3.0 μm), and in the size of their terminal boutons (from 0.5 to 3.5 μm). Bouton size increased with increasing diameter of the parent axon. The great majority of arbors are confined to one of three retinorecipient sublayers in the superficial tectum. However, the full range of arbor sizes and axon diameters is present in each sublayer.
Glial cells of an insect ganglion
Authors: Hoyle Graham 
Published: January 2005

AbstractThe rapid development of the study of insect neurobiology, which is currently occurring principally because individual neurons can be re‐identifled and because their activities can be recorded in situ and related to behavior, is generating a demand for more knowledge concerning insect glial cells and their functional relationships with neurons. This study examines the ultrastructure of glial cells in locust metathoracic ganglia in relation to general locale within the ganglion and also to specific identified neurons and neuron types. Seven major types of glial cell form are recognized, with subdivisions, requiring a new scheme for classification. Glial invaginations into neurons are of four different kinds: regular, chunky, filigree, and ridge (found only at axon hillocks). They also range from only intrusive to fully reciprocal. In addition, some neurons make projections of various lengths into surrounding glia and between neighboring neuron somata, and some glia make long, branched projections into other glial cells. The differences show that insect glial cells develop highly specific functional specializations; they may not be interchangeable. The complexity and intimacy of relationships of glia with neurons suggest that some glial cells may have roles other than that of nursemaids, possibly in modulation of behaviordetermining neural activity, and in learning and other adaptive acts.