bluuebunny/crossref_metadata_2025_split huggingface dataset:
The number and distribution of ganglion cells in the retina of the brush‐tailed possum, Trichosurus vulpecula
Authors: Freeman Brian , Tancred Elizabeth 
Published: January 2005

AbstractThe distribution of ganglion cells in the retina of the adult brush‐tailed possum was determined by light microscopy of Nissl stained retinal whole mounts. Qualitatively, the distribution in this marsupial retina shows features, such as an area centralis and a visual streak, which are found separately or together in eutherian mammals. The possum retina is avascular and the eye has a weak tapetumin the superior fundus.The retinal area is 260 mm2 and there are about 280,000 ganglion cells. The diameters of the ganglion cell somas range from 5μm to 26μm and the frequency distribution of soma size classes is skewed and unimodal (mean: 12.8μm) with 62% of the cells falling in the class of diameters 7‐13μm. Maps of ganglion cell density were made for five retinae. These mapsshow that there is a band of high ganglion cell density (> 2,000 cells mm−2) which extends across the retina about 0.6 mm above the optic disc in the tapetal region of the fundus and which lies in the plane of the animal's horizon when the eyes are in their primary position. By analogy with other species, this band is termed the visual streak. Near the temporal end of the visual streak, 2.9 mm from the optic disc, the ganglion cell density reaches a localized maximum of approximately 5,000 cells mm−2 thereby defining the centre of an area centralis (> 3,000 cells mm−2). The posterior nodal distance of the possum eye was estimated at 7.8 mm, which correspondsto a retinal magnification of 136μm per degree of visual field. There are up to 30,000 glial cells which lie in, or slightly vitread to, the layer of the retinal ganglion cells.
Anatomical observations on the dorsal column nuclei, their thalamic projection and the cytoarchitecture of some somatosensory thalamic nuclei in the monkey
Authors: Boivie Jörgen 
Published: January 2005

AbstractThe results of the present anatomical study on macaque monkeys concern some aspects of the dorsal column nuclei, their projection to the thalamus and the cytoarchitecture and topography of the recipient areas in the thalamus for the somatosensory pathways. Some observations regarding the cytoarchitecture of the dorsal column nuclei are reported; the gracile nucleus differs cytoarchitectonically over the rostrocaudal dimension in a way similar to the feline nucleus; the cuneate nucleus has a distinct pars rotunda (Ferraro and Barrera, '35) which might be analogous to a similar structure in the raccoon shown to be activated by afferents from the volar side of the hand and digits (Johnson et al., '68). Cytoarchitectonic observations and other arguments suggesting the presence of the nucleus Z in the monkey are presented.In Nissl stained frontal sections, cut in the stereotaxic frontal plane as well as in sections cut perpendicular to the long axis of the brain stem the cytoarchitecture and topography of the posteromedial, ventroposterior and centrolateral thalamic nuclei of the macaque were analysed. The posteromedial nucleus (POm) has been found to include portions of Olszewski's ('52) magnocellular medial geniculate, suprageniculate and pulvinar nuclei. The nucleus ventralis posterolateralis (VPL) corresponds to the main portion of Olszewski's VPLc, whereas most of his VPLo corresponds to the nucleus ventralis intermedius of Hassler ('59) and Mehler ('71).Electrolytic lesions were used to study the projection from the gracile and cuneate nuclei to the thalamus. With postoperative survival periods of 6 to 14 days the resulting degeneration was studied in frontal sections stained according to the Wiitanen modification of the Fink‐Heimer method. Both the gracile and cuneate nuclei project profusely to the contralateral nucleus ventralis posterolateralis and more sparsely to the contralateral posteromedial nucleus and the zona incerta. A distinct somatotopic organization exists in the projection to the ventroposterior nucleus, but not in that to the other target areas. The projection to the ventroposterior nucleus is very dense and evenly distributed except rostrally and dorsally, where it is more scattered.It is concluded that the posteromedial and the ventroposterior thalamic nuclei are very similar in monkeys and cats regarding cytoarchitecture, topography and afferent projections from the dorsal column nuclei.
Organization of the mossy fiber system of the rat studied in extended hippocampi. I. Terminal area related to number of granule and pyramidal cells
Authors: Gaarskjaer Frank B. 
Published: January 2005

AbstractA quantitative and qualitative study of the septotemporal organization of the hippocampal mossy fiber system has been carried out in the rat. Transverse sections of isolated and extended hippocampi were stained according to Nisel's or Timm's method. At 12 equidistant levels covering the entire length of the hippocampus the following parameters were measured: the length of the granule cell layer and the mossy fiber layer, the area of the fields containing mossy fiber boutons, the number of granule cells, and the number of pyramidal cells in the hilus and in the regio inferior.Septally the pyramidal layer of the regio inferior is broad and the cells within the layer are relatively widely spaced. Here the mossy fiber boutons intrude deep into the layer. At more temporal levels the cells are tightly packed, the cell‐layer is narrower, and the boutons predominantly terminate suprapyramidally.The length of the granular layer is greatest septally, while the length of the mossy fiber layer is greatest temporally. The area of the hilus, occupied by the mossy fiber boutons, is large at most of the temporal levels and small at the septal levels, whereas in CA3 the reverse is true. The greatest number of granule cells was found at the more septal levels. Conversely, the majority of the pyramidal cells in the hilus and in the regio inferior is situated temporally. The ratio of granule cells to pyramidal cells (hilus and regio inferior together) declines linearly from approximately ten at septal levels to approximately one at temporal levels. Because the mossy fibers are distributed fairly transverse to the long axis of the hippocampus, the variation in the ratio of granule cells to pyramidal cells reflects a corresponding variation in the number of innervating to innervated cells within the mossy fiber system.
The motor column and sensory projections of the branchial cranial nerves in the frog
Authors: Matesz Clara , Székely George 
Published: January 2005

AbstractMotor nuclei and primary afferent projections of branchial cranial nerves were shown with the CoCl2 staining technique. Motor nuclei constitute a discontinuous column at the ventrolateral margin of the gray matter. The size of motoneurons decreases in the orocaudal direction within the column. The dendrites assemble in two main directions forming a dorsomedial and a ventrolateral dendritic array. The axons originate in the ventrolateral dendrites and run straight to the motor roots. Preganglionic vegetative neurons were found in a separate group at the level of the abducens nucleus, and intermingled with motoneurons at the level of the glossopharyngeus and vagus nuclei. Their axons join the visceral sensory roots of the respective nerve.The tractus spinalia trigemini has a short and weak ascending limb, and a strong descending limb which decussates in the first and second segments of the spinal cord. A few uncrossed large fibers continue as far as the midthoracic level, In addition to trigeminal fibers, a small contingent of facial fibers and a significant number of vagus fibers contribute to the tractus spinalis. Small caliber fibers of the tractus and fine collaterals of large caliber fibers terminate in a continuous column which lies, in its largest part, in the neuropil medial to the tractus. The pattern of fiber terminations in this area is identical with that in the substantia gelatinosa. This area is called the nucleus spinalis trigemini. Coarse collaterals terminate in a discontinuous column of large and medium‐sized neurons, extending caudally to the obex region. This area is the largest at the level of the trigeminus nucleus and is called the nucleus principalis trigemini.The cells of origin of the mesencephalic tractus of the trigeminus lie in the second and fourth layers of the optic tectum. The descending fibers run ventral to the tractus spinalis in a separate bundle. They emit collaterals to the large fiber termination areas and to branchiomotor nuclei. Direct contacts are established with trigeminus motoneurons. In the obex region a significant number of collaterals invade the dorsomedial part of the gray matter.The fasciculus solitarius begins at the level of the trigeminal nucleus and terminates in the commissura infima at the medullospinal border. The nucleus solitarius begins at the oral pole of the glossopharyngeus nucleus. The fasciculus receives fibers from the facialis (intermedius), glossopharyngeus and vagus nerves. The fibers spread over the total extent of the fasciculus: the facialis fibers exhibit a preference for a dorsomedial position and the glossopharyngeusvagus fibers for a ventrolateral position. There are several interchanging fibers between the somatic sensory and visceral sensory projecting areas.The results indicate a close similarity between amphibian and mammalian brain stem motor nuclei and sensory projections, though some parts are present in a primordial form in the frog.
An anterograde degeneration study of the tangential spread of axons in cortical areas 17 and 18 of the squirrel monkey (Saimiri Sciureus)
Authors: Colonnier M. , Sas E. 
Published: January 2005

AbstractIn area 17 of squirrel monkey, lamina IVB of Brodmann is divided into three sublaminae by a thin, dense row of cell bodies, the largest of which have apical poles. Study of the 17/18 border suggests that these are a group of pyramidal cells, continuous with the large border pyramids in the depth of layer III in area 18. In contrast, the densely packed granule cells of layers IVA and IVC appear to be continuous with those of layer IV of area 18. It is thus proposed that in area 17, the third and fourth neocortical layers not only divide into sublaminae, but that these in turn interdigitate and intermingle their cell types. The tangential extent of intracortical fibers has been studied by making perpendicular slits in both areas and measuring the spread of anterograde degeneration to each side of the lesion. In area 17, this spread is always the same whatever the orientation of the fibers with respect to visual field representation. Degenerating fibers are few in number and found mainly in layers I, IVB and VI. In layers IVB and VI they extend for 0.5–1.0 mm. In layer I, some reach as far as 2.0 mm. In area 18, degenerating fibers are more numerous and longer. They are plentiful in layer I, diminish considerably in layer II, increase again in number till the depth of III, are slightly less numerous in layer IV and are again plentiful in layers V and VI. Their length varies with orientation. In a direction corresponding to a visual field sector, they extend for 1.5–2.0 mm, a distance representing only a fraction of the total representation of a sector in the cortex. In a direction corresponding to a visual field zone, they extend further and the combined degeneration of the two sides spans the whole distance of area 18 from the vertical to the horizontal meridian (6 mm). It is suggested that at least some of the fibers of the stria of Gennari subserve binocular interaction and that the differential fiber lengths in area 18 are related to foveal acquisition or to a directional anisotropy of visual movement perception along sector‐zone axes.
Regional variations in glia and neuropil within the hypothalamic ventromedial nucleus
Authors: van Houten Mark , Brawer James R. 
Published: January 2005

AbstractThe normal fine structure of glia and neuropil in the various regional subdivisions of the hypothalamic ventromedial nucleus in the adult male albino rat is described in this report. Although most HVM astrocytes throughout the nucleus appear ordinary in cytology, certain astrocytes found in the posterior ventrolateral subdivision of the nucleus appear somewhat reactive, in that they contain numerous thick fascicles of gliofibrils and pleomorphic dense bodies. The processes of these reactive astrocytes elaborate multiple, concentric lamellae which encapsulate small, round, pyknotic masses (probably degenerate axonal elements). These degenerate profiles, which are greatly outnumbered by normal HVM boutons, may represent synaptic contacts that deteriorate spontaneously in the normal adult HVM. Other signs of spontaneous degeneration occurring within this neuropil include the occasional presence of large masses of necrotic debris which appear engulfed by microglia. These findings suggest the presence in the normal adult HVM neuropil of a low‐grade degenerative process with attendant gliosis, which is topographically centered about the posterior ventrolateral region of the nucleus.Regions of neuropil containing degenerate boutons also contain altered neuronal processes, some of which may be growth cones. The topographic proximity of the degenerating boutons to possible signs of axonal or dendritic regeneration indicates that certain synaptic circuits in the normal adult HVM may be plastic, and subject to spontaneous remodelling.
Studies of visual function and its decay in mice with hereditary retinal degeneration
Authors: Dräger Ursula C. , Hubel David H. 
Published: January 2005

AbstractFunctional implications of mouse hereditary retinal degeneration have been studied at the level of the superior colliculus and visual cortex in the C57BL/6J‐le rd strain. On autoradiography at a light‐microscopic level, following eye injection with radioactive compounds, central visual structures appeared normal. A slight reduction in ipsilateral retinal projection was probably related to reduced retinal pigmentation associated with the light ear (le) mutation. In recordings from visual cortex and tectum in rd mice older than five months the cells discharged with highly rhythmic maintained activity. This ongoing activity depended on retinal input, since temporary asphyxia of the eye stopped it immediately. The frequency of the rhythm was influenced by the anesthesia. In these older mice no visual receptive fields could be mapped, but in a few tectal recordings it was possible to suppress the maintained activity by diffuse, very intense illumination. As in normal mice, no auditory or somatosensory responses were observed in the visual cortex or upper tectal layers. In recordings from tectum before the age of three weeks retinotopic topography and receptive fields were normal. By day 24 no receptive fields could be recorded from parts of the tectum representing the central 90‐100° of the visual field, whereas within a peripheral ring responses were still roughly normal under photopic conditions. Over the following four months these peripheral responses faded away slowly. Incremental thresholds, especially in the scotopic range, were elevated, rising slowly to unmeasurable values. Similarly during dark adaptation the thresholds fell to values several log units above those reached in normal mice; these values of dark adapted thresholds in rd mice rose with age. This is consistent with morphological changes known to occur in the retina as a consequence, of the rd mutation the rods degenerating before the cones.
Radioautographic investigation of gliogenesis in the corpus callosum of young rats II. Origin of microglial cells
Authors: Imamoto Kikuko , Leblond C. P. 
Published: January 2005

AbstractMicroglial cells are absent from the corpus callosum of newborn rats. In the hope of finding out when and how microglial cells appear with age, 3H‐thymidine was given intraperitoneally as single or three shortly spaced injections to 5‐day‐old rats weighing about 15 g; and these animals were sacrificed at various time intervals from 2 hours to 35 days later. Pieces of corpus callosum were taken near the superior lateral angle of the lateral ventricles; and semithin sections were radioautographed and stained with toluidine blue.The corpus callosum of 5‐day‐old rats is composed of loosely arranged unmyelinated fibers and scattered cells. Among these cells, microglia are rare; there are a few astrocytes, many immature glial cells, rare pericytes, and 6‐7% of phagocytic “ameboid cells” consisting of a few monocytes and many macrophages. In the animals sacrificed two hours after 3H‐thymidine administration, label is present only in immature cells and “ameboid cells.”As time elapses and the fibers of corpus callosum become myelinated, oligodendrocytes and, later, microglial cells appear. At the age of 12 days, microglial cells are present in substantial number; and by 19 days, the number doubles to reach a plateau. Many of the new microglial cells are labeled, e.g., 78.1% in 12‐day‐old animals (7 days after 3H‐thymidine administration). The labeled microglial cells must have come from the transformation of cells that acquired label early, that is, from the immature cells or the “ameboid cells.” The height of the peaks of labeling – 59.8% at nine days for immature cells and 77.8% at 12 days for “ameboid cells” – points to the latter as precursors of the highly labeled microglial cells. Furthermore, the “ameboid cells” disappear as microglial cells appear and there are transitional elements between these two cell types. Cell counts suggest that about a third of the “ameboid cells” transform into microglial cells, while the others degenerate and die.Thus, the microglial cells which appear in the corpus callosum during the first three weeks of life result from transformation of the “ameboid cells” – a group of macrophages showing various stages of transition from monocytes. As for the occasional microglial cell appearing after the third week or in the adult, they presumably come directly from monocytes. In either case, monocytes would be the intial precursors.
Immunohistochemical localization of enkephalin in rat brain and spinal cord
Authors: Sar Madhabananda , Stumpf Walter E. , Miller Richard J. , Chang Kwen‐Jen , Cuatrecasas Pedro 
Published: January 2005

AbstractThe distribution of immunoreactive enkephalin in rat brain and spinal cord was studied by immunoperoxidase staining using antiserum to leucine‐enkephalin ([Leu5]‐enkephalin) or methionine‐enkephalin ([Met5]‐enkephalin). Immunoreactive staining for both enkephalins was similarly observed in nerve fibers, terminals and cell bodies in many regions of the central nervous system. Staining of perikarya was detected in hypophysectomized rats or colchicine pretretated rats. The regions of localization for enkephalin fibers and terminals include in the forebrain: lateral septum, central nucleus of the amygdala, area CA2 of the hippocampus, certain regions of the cortex, corpus striatum, bed nucleus of the stria terminalis, hypothalamus including median eminence, thalamus and subthalamus; in the midbrain: nucleus interpeduncularis, periaqueductal gray and reticular formation; in the hind brain: nucleus parabrachialis, locus ceruleus, nuclei raphes, nucleus cochlearis, nuclear tractus solitarii, nucleus spinalis nervi trigemini, motor nuclei of certain cranial nerves, nucleus commissuralis and formatio reticularis; and in the spinal cord the substantia gelatinosa. In contrast enkephalin cell bodies appear sparsely distributed in the telencephalon, diencephelon, mensencephalon and rhombencephalon. The results of the histochemical staining show that certain structures which positively stain for enkephalin closely correspond to the distribution of opiate receptors in the brain and thus support the concept that the endogenous opiate peptides are involved in the perception of pain and analgesia. The localization of enkephalin in the preoptic‐hypothalamic region together with the presence of enkephalin perikarya in the paraventricular and supraoptic nuclei suggest a role of enkephalin in the regulation of neuroendocrine functions.
The neurological organization of pathways between the dorsal lateral geniculate nucleus and visual cortex in old world and new world primates
Authors: Henderickson Anita E. , Wilson James R. , Ogren Marilee P. 
Published: January 2005

AbstractPathways between the dorsal lateral geniculate nucleus (dLGN) and visual cortex in Old World (Macaca, Papio, Erythrocebus, Cercopithecus) and New World (Saimiri, Cebus) primates were studied after injections of horseradish peroxidase and H3 or S35 amino acids into the dLGN or visual cortex. Trans‐synaptic autoradiography was also used to study these pathways after an injection of H3 proline‐fucose into one eye. The subsequent autoradiographs of visual cortex showed that Old World primates have separate eye inputs (ocular dominance columns) in striate cortex, whereas New World monkeys have overlapping or non‐separated eye inputs. In both primate groups the geniculocortical input to layer IVA formed a pattern which resembled a honeycomb in tangential sections, unlike the solidly labeled layer IVC. Also common to the two primate groups was a projection from dLGN to layer VI. There was no dLGN projection to any prestriate area in any of the primates. However, after an injection limited to the prestriate cortex of Macaca, light autoradiographic labeling was seen in the interlaminar zones and the magnocellular and S laminae, demonstrating a prestriate‐dLGN pathway.Our results indicate that the primate visual system differs significantly from the cat in having no dLGN projection to area 18. There are also significant differences between primates in the level at which the possibility of binocularity (of an excitatory nature) first occurs in the striate cortex because in the species studied thus far with neuroanatomical methods, Old World primates have ocular dominance columns in layer IV but most New World monkeys lack them.
Termination of electroreceptor and mechanical lateral line afferents in the mormyrid acousticolateral area
Authors: Bell Curtis C. , Russell Charles J. 
Published: January 2005

AbstractThe projection regions of electroreceptor and mechanical lateral line afferents in electric fish of the mormyridae family are described.Electroreceptor afferents from the posterior dorsal skin run in the dorsal branch of the posterior lateral line nerve. Electroreceptor afferents from ventral skin and mechanical lateral line afferents and efferents run in the ventral branch of the nerve. Horseradish peroxidase (HRP) injections into each branch resulted in filling of its central terminals with the marker enzyme. The method yields a Golgi‐like staining of afferent terminals, allowing some aspects of their morphology to be described. Comparison of results from dorsal and ventral branch injections shows the separate medullary regions to which electroreceptor and mechanical afferents project, and also demonstrates four separate somatotopic maps within the electroreceptor region.Mechanical afferents end predominantly ipsilaterally in nucleus anterior and eminentia granularis as has been suggested by others. Ipsilateral endings in nucleus octavius are also seen. Electroreceptor afferents end exclusively in the cortex and nucleus of posterior lateral line lobe (PLLL). Within the cortex there are three distinct maps of the skin surface which are separated from each other by discontinuities in the cellular layers. Somatotopic mapping is also present in the nucleus of PLLL though it is less precise than in the cortical zones. Large club endings of the cells of this nucleus are filled with HRP. Labeled cells are seen within a small midline nucleus located at the level of the eighth nerve just above the medial longitudinal fasciculus. These are probably the cell bodies of lateral line efferents.