bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anatomy of the cerebral ganglion of the female acanthocephalan, Macracanthorhynchus hirudinaceus
Authors: Miller Donald M. , Dunagan T. T. , Richardson John 
Published: May 2005

AbstractAn atlas of the cerebral ganglion of M. hirudinaceus has been constructed and the cells identified by number. There is a total of eighty‐six cells, three of which are binucleate. These cells (30, 80 and 90) are located in the frontal plane. Most cells give rise to bilateral processes and are organized in such a way that there is an outer coat of somata or cell bodies and a center core or neuropile. Some cell processes are 8 μ in diameter and most exit the ganglion via nerves of the opposite side. The cytoarchitecture of these cells indicates most have perinuclear rings and a well defined nucleolus. However, considerable variation occurs in number and distribution of cytoplasmic granules.
A combined fluorescence histochemical and electron microscopic method for studying special monoamine‐containing cells (SIF cells)
Authors: Grillo Mary A. , Jacobs Louise , Comroe Julius H. 
Published: May 2005

AbstractThis paper describes a method for locating “small intensely fluorescent” (SIF) cells on the basis of their monoamine fluorescence preparatory to study with the electron microscope. After fixation by perfusion with a formal‐dehyde‐glutaraldehyde mixture, the cells develop a bright yellow fluorescence easily seen when thick, unembedded slices of ganglionic tissue are examined with fluorescence optics. Once located, the same cells can then be studied electronmicroscopically following a second fixation with osmium tetroxide and Epon embedding. The resultant images are of good quality and highly reproducible. As an alternative to extensive sampling of plastic‐embedded ganglia, the method has the advantage of being less time‐consuming and more informative. Cells stored in fixative for months or embedded in paraffin retain their specific fluorescence. Since the particular fixative used is compatible with a variety of neurohistological and histochemical techniques, the method provides unprecedented opportunities for correlative studies employing fluorescence, light, and electron microscopy.The method can also be applied to glomus cells of the carotid and aortic bodies and to adrenal medullary cells.
Synaptic termination of afferents from the ventrolateral nucleus of the thalamus in the cat motor cortex. A light and electron microscope study
Authors: Strick Peter L. , Sterling Peter 
Published: May 2005

AbstractThe synaptic termination in the cat motor cortex of afferents from the ventrolateral nucleus of the thalamus (VL) has been studied with experimental light and electron microscopic methods. The distribution of normal synapses on motor cortex pyramidal, stellate, and Betz cells was also examined.Synapses in the motor cortex can be classified into two general types. The first and most prominent type contains flat vesicles, lacks a compact postsynaptic density, and corresponds to Colonnier's ('68) symmetrical synapse.Stellate neurons receive synapses of both types on their cell bodies and proximal dendritic shafts, while pyramidal cells have only symmetrical synapses at these sites. The dendritic spines of both stellate and pyramidal cells are contacted by predominantly asymmetrical synapses. Betz cells, like smaller pyramidal neurons, receive only symmetrical synapses on their cell bodies. The proximal portions of the Betz cells apical dendrites, however, receive both asymmetrical and symmetrical synapses.Following VL lesions, degenerating synapses were mainly found in three cortical layers: the upper third of layer I (18%), layer III (66%), and layer VI (13%). Degenerating synapses were not seen in the lower two‐thirds of layer I or in layer II, and were only rarely seen in layer V (3%).Ninety‐one percent of the VL synapses were found on spines and 8% on stellate‐type dendritic shafts. Stellate cell bodies rarely received VL synapses (1%) and none occurred on pyramidal or Betz cell bodies and their proximal dendrites. A VL synapse within layer III was found on two dendritic spines of a Betz cell apical dendrite. Thus, part of the VL input to layer III synapses on the processes of both motor cortex output neurons (Betz cells in layer V) and cortical interneurons (stellate cells in layer III).
Lamination of the dorsal lateral geniculate nucleus in carnivores of the weasel (Mustelidae), Raccoon (Procyonidae) and Fox (Canidae) families
Authors: Sanderson K. J. 
Published: May 2005

AbstractThe laminar structure of the dorsal lateral geniculate nucleus was studied in carnivores of the weasel, raccoon and fox families. All have the same basic pattern of laminar organization in their lateral geniculate nuclei. Laminae A and C receive a contralateral projection from the retina and laminae A1 and C1 receive an ipsilateral projection. It is not known whether lamina C2 receives a retinal projection.There are some variations to the basic pattern of laminar organization. Thus, in the mink and weasel laminae A and A1 are each subdivided into a pair of separate but similar leaflets. In the ferret and coatimundi these laminae are only partly subdivided. In the skunk, raccoon, ringtailed cat and fox there is only one lamina A and one lamina A1 in each lateral geniculate nucleus. There is some variation of the C laminae also. The C laminae are best displayed in the fox, where all three laminae — C, C1 and C2 — can be recognized in Nissl sections. In other carnivores, for example the mink and ferret, the C laminae cannot be distinguished from each other in normal brains and are described on the basis of the degeneration that is seen in Nauta and Fink‐Heimer sections after a unilateral enucleation. In the raccoon lamina C can be identified but lamina C1 may be missing.The perigeniculate nucleus is variable in structure in carnivores. In the weasel and raccoon family the perigeniculate nucleus is a thick layer containing many large cells while in the cat and fox, it is a thin and rather diffuse group of cells. The perigeniculate nucleus may receive a direct retinal projection but if so, it is only a very sparse one.
Intraretinal differentiation in the synaptic organization of the inner plexiform layer of the pigeon retina
Authors: Yazulla Stephen 
Published: May 2005

AbstractThe inner plexiform layer at ten retinal loci in pigeon was examined by electron microscopy. Photomontages of the entire depth of the inner plexiform layer at each locus were analyzed with respect to the number of amacrine and bipolar synapses, their respective ratios, synaptic densities, percent amacrine synapses in serial configuration, synaptic layering patterns, and the effect of staining procedures on these quantities. The results show that the pigeon retina is not homogeneous regarding the structural complexity of the inner plexiform layer, but may be divided into four general areas in decreasing order of complexity: red field, temporal yellow field, nasal yellow field, and the area centralis. Significant differences in the amacrine synapse to bipolar synapse ration and amacrine synaptic density were observed across the retina, while bi‐polar synaptic density and the percent of serial synapses were rather constant. Amacrine synapses displayed a layering pattern which was consistent throughout the retina; while bipolar synapses showed two patterns. It was further observed that the density of amacrine and bipolar synapses bears little relationship to the density of amacrine and bipolar cells in the immediately overlying inner nuclear layer. This suggests that the various retinal loci may be characterized by different proportions of the morphological types of amacrine and bipolar cells present in the pigeon retina. Based on recent studies which have shown that a relationship exists between the complexity of ganglion cell receptive fields and the synaptic complexity of the inner plexiform layer, it is suggested that the ganglion cells of pigeon would show a physiological differentiation among retinal loci consistent with the observed differences in the anatomical complexity of the inner plexiform layer.
Scanning electron microscopy of the subarachnoid space in the dog. I. Spinal cord levels
Authors: Cloyd Miles W. , Low Frank N. 
Published: May 2005

AbstractYoung dogs six to 14 weeks old were perfused with aldehydes by standard techniques followed by MICROFIL to prevent blood vessel collapse. Tissue pieces possessing natural surfaces of the subarachnoid space at spinal cord levels were removed, post‐osmicated, dehydrated, critical point dried, coated with palladium‐gold and examined in a Cambridge Stereoscan S4 scanning electron microscope.The surfaces of the spinal pia mater and arachnoid are clearly expressions of connective tissues with fenestrations and underlying connective tissue fibrils. Fenestrations are especially common in the conus medullaris where connective tissue fibrils are more likely exposed to cerebrospinal fluid than covered by pial lining cells. Long and short microvillae and blebs are present in profusion and with distributions comparable to the same structures on other cells. The surfaces of traversing structures; blood vessels, nerve roots, arachnoid trabeculae and denticulate ligaments are covered with tissues comparable to and continuous with pia and arachnoid despite underlying differences in histological makeup. Free cells are present on all spinal leptomeningeal surfaces in surprising profusion. They exhibit extreme pleomorphism of surface contours which is comparable to that observed in the scanning electron microscopy of cells from other sources. It is highly probable that these free cells are macrophages.
The morphology of retinal neurons of the owl monkey aotes
Authors: Ogden Thomas E. 
Published: May 2005

AbstractThe morphology of photoreceptor, horizontal, bipolar and amacrine cells of the owl monkey (Aotes) is described from retinal whole mounts and cross sections stained with the method of Golgi (Colonnier modification).Rods and cones were often seen and resemble the photoreceptors of other primates. Cone density may be as great as 6400/mm2. Horizontal cells in the area centralis are larger and contact more cones than is the case with rhesus. Peripheral horizontal cells of Aotes are similar to those of rhesus. Midget bipolar cells are common and, even in the area centralis, usually have two basal dendrites. Only midget bipolars with invaginating terminals were clearly identified. Rod and flat bipolars were clearly identified and resembled those of rhesus. A “diffuse” bipolar is described which may represent a variant of either rod or flat bipolar. Some of these cells had dendritic spreads greater than 60 μ. Such bipolar cells have not been described in other primates. Amacrine cells were similar to those of rhesus except that those with coarse processes were all diffuse, i.e., their processes extended vertically through the IPL; those with fine processes were all stratified; their processes were restricted to a narrow lamina of the IPL.
Development of the extrinsic connections of the visual cortex in the cat
Authors: Anker Robyn L. , Cragg Brian G. 
Published: May 2005

AbstractLesions were made in the visual system in a series of kittens, and fiber degeneration stained by the Eager or Fink‐Heimer methods. Stereotaxic lesions made in the lateral geniculate nucleus (LGN) in one day old kittens led to the appearance of finely dotted fiber degenerationn in area 17 (concentrated in layer IV) two days later. Thalamic lesions involving the LGN in older kittens caused fiber degeneration in the other visual areas. This was first seen in the lateral suprasylvian gyrus (SSG) at six days, in area 19 at 14 days, and in area 18 at 21 days.Lesions of visual cortex affecting areas 17 and 18 caused degeneration of descending connections to the LGN, lateralis posterior and superior colliculus when made in kittens one day old. However, ipsilateral cortical connections to area 19 were not seen until the kittens were 19 days old at operation, and connections to the suprasylvian gyrus appeared at 21 days. Contralateral cortical connections carried by the corpus callosum were not seen until the kittens were 26 days old at operation, and a distribution of degeneration comparable with that seen in adults was present at 40 days.This time sequence of development is discussed in relation to what is known about the time of development of functioning in the cat's visual system.
Efferent fibers of the deep cerebellar nuclei in hedgehogs
Authors: Earle Alvin M. , Matzke Howard A. 
Published: May 2005

AbstractThree main deep cerbellar nuclei are apparent in hedgehogs belonging to the genera Erinaceus and Hemiechinus; however, at various levels they exhibit a considerable continuity with one another. Electrolytic unilateral lesions were placed in the deep cerebellar nuclei of these hedgehogs, and additional animals were subjected to a midline incision of the cerebellum between the two fastigial nuclei. Degenerating axons were traced from the sites of lesions using the Nauta and Fink‐Heimer techniques.The typical mammalian pattern is evident in the distribution of the cerebellifugal fibers of the hedgehog. Crossed and uncrossed fastigial efferent fibers are directed primarily toward vestibular nuclei and the bulbar reticular formation except for a relatively small ascending limb of the uncinate fasciculus. The brachium conjunctivum originates from the nucleus interpositus and nucleus lateralis. The efferents of these nuclei are directed rostrally to the contralateral red nucleus. Fibers passing beyond the level of the red nucleus terminate in the thalamic nuclei. Fibers from the brachium conjunctivun also supply the inferior and superior colliculi. Axons forming the descending limb of the brachium conjunctivum are divided into medial and lateral fascicles.
Synaptic interactions of identified nerve cells in the spinal cord of the sea lamprey
Authors: Rovainen Carl M. 
Published: May 2005

AbstractAs part of a continuing study on the organization of the lamprey nervous system, two additional groups of interneurons have been identified by physiological and morphological criteria in the isolated spinal cord of Petromyzon marinus. These and other identified nerve cells were tested for synaptic interactions using separate intracellular microelectrodes for stimulation and recording.
Edge cells were identified by their unusual location in the lateral fiber tracts of the spinal cord. Their axons extended rostrally either on the ipsilateral or contralateral side of the cord.
Some edge cells showed polysynaptic EPSP's and IPSP's after stimulation of sensory dorsal cells, but interactions with other identified neurons were rare. A single cell was excited by a giant interneuron. One edge cell produced IPSP's in a contralateral edge cell, and another produced IPSP's in lateral cells on the opposite side of the spinal cord. Thus, some edge cells have an inhibitory function.
Lateral cells were distinguished from giant interneurons and edge cells by their cell bodies in the lateral grey of the spinal cord in the gill and trunk regions, their ipsilateral dendrites, and their long ipsilateral axons extending as far as the tail.
Lateral cells were excited and inhibited polysynaptically by sensory dorsal cells and, in turn, produced weak IPSP's in unidentified neurons. Stimulation of lateral cells produced neither visible movements peripherally nor synaptic potentials in other lateral cells, in giant interneurons, or in edge cells.
Giant interneurons were previously identified on the basis of their cell bodies in the caudal half of the spinal cord, their bilateral dendrites, and their long contralateral axons extending towards the brain. Giant interneurons exhibited unitary composite EPSP's when more caudal giant interneurons were stimulated. The two components of the EPSP were due to electrical and chemical transmission. Under the electron microscope a contact between a dendrite of one giant interneuron and the probable axon of another had separate junctions resembling chemical and electrical synapses.
Intracellular stimulation of sensory dorsal cells produced both monosynaptic and polysynaptic EPSP's in giant interneurons. Some dorsal cells produced unitary composite EPSP's Giant interneurons are part of a convergent, multispecific sensory system extending towards the brain.
The relationship between morphogenetic cell death and the development of congenital anophthalmia
Authors: Silver J. , Hughes A. F. W. 
Published: May 2005

AbstractGlücksmann ('51) observed that during normal mammalin ocular morphogenesis large numbers of cells become necrotic and are resorbed within the eye rudiment prior to and during invagination of the optic cup. Silver and Hughes ('73) observed that these resorptions are largely confined to the ventral aspect of the optic rudiment where the optic fissure subsequently forms. Evidence for the role of cell death during fissure formation and other morphogenetic events during eye development has remained unclear, however, since the quantity of degenerate cells cannot be selectively controlled in developing tissue by experimental means (Saunders, '66).Chase et al. ('41a) described a congenitally anophthalmic strain of mice in which, he proposed, retarded growth of the eye vesicle and the consequent failure of lens induction result in approximately 90% eyeless and 10% microphthalmic neonates. Upon reexamination of a sequence of embryos of the eyeless strain it was observed that during the earliest stages of ocular morphogenesis the regular sequence of necrotic loci, which Silver and Hughes ('73) have described in rat and other mammalin embryos, is entirely lacking.Our observations suggest that the first recognizable divergence between the morphology of timed mutant (strain zrdct‐an) and control embryos (strain C57BL/6J) occurs during apposition of the optic vesicle and surface ectoderm but prior to the development of the retinal thickening and lens placode. In control embryos mesenchyme which becomes entrapped between the prospective retina and lens becomes necrotic and is resorbed. Conversely, in eyeless embryos the surfaces of the presumptive retina and lens, while closely apposed, are separated by variable numbers of mesenchymal cells which remain viable and can undergo mitoses throughout development. The failure of mesenchymal cells to degenerate may lead to the reduction in size of both retina and lens primordia. Contrary to Chase's ('41a) observations, in all anophthalmic embryos contact between the optic vesicle and lens epithelium is eventually established and a lens of variable size is induced. In most cases, however, the lens is displaced from the eye chamber by proliferation of the mesenchymal cell mass and the optic rudiment is subsequently resorbed. In the remaining embryos which presumably will become microphthalmic the lens reaches a critical dimension and is retained within the eye cup. In them, although cell death is absent from within the developing eye vesicle and cup, invagination can proceed as far as the retinal fissure stage. However, the optic fissure does not form. These observations suggest that there may be a relationship between morphogenetic cell death, formation of the optic fissure, and the production of severe congenital eye defects.
Developmental changes in neuron size and density in the visual cortex and superior colliculus of the postnatal golden hamster
Authors: Ptacek James M. , Fagan‐Dubin L. 
Published: May 2005

AbstractPostnatal changes in neuron cell body diameter and neuron density were observed in newborn, two‐week old, and eight‐week old golden hamsters. Quantitative data indicated that in both the visual cortex and superior colliculus, neuron cell body diameter increased nearly twofold during the first two‐week period following birth and reached maximum size by approximately day 14, the stage at which eye opening usually occurs. Neuronal density was highest in the newborn and decreased with age in both visual centers. The decreased neuronal density and, thus, increased neuropil area may reflect a greater number of synaptic connections mediating visual function. Although the development in the visual cortex paralleled that in the superior colliculus, the superior colliculus seemed to mature earlier than the visual cortex, possibly related to its more primitive evolutionary role.
Sequence regularity and geometry of orientation columns in the monkey striate cortex
Authors: Hubel David H. , Wiesel Torsten N. 
Published: May 2005

AbstractThe striate cortex of the macaque monkey is subdivided into two independent and overlapping systems of columns termed “orientation columns” and “ocular dominance columns.” The present paper is concerned with the orientation columns, particularly their geometry and the relationship between successive columns. The arrangement of the columns is highly ordered; in the great majority of oblique or tangential microelectrode penetrations the preferred orientations of cells changed systematically with electrode position, in a clockwise or counterclockwise direction. Graphs of orientation vs. electrode track distance were virtually straight lines over distances of up to several millimeters; such orderly sequences were often terminated by sudden changes in the direction of orientation shifts, from clockwise to counterclockwise or back. The orientations at which these reversals occurred were quite unpredictable. Total rotations of 180–360° were frequently seen between reversals. In tangential or almost tangential penetrations orientation shifts occurred almost every time the electrode was moved forward, indicating that the columns were either not discrete or had a thickness of less than 25–50 μ, the smallest order of distance that our methods could resolve. In penetrations that were almost perpendicular to the surface, the graphs of orientation vs. track distance were relatively flatter, as expected if the surfaces of constant orientation are perpendicular to the cortical surface. Stepwise changes in orientation of about 10° could sometimes be seen in perpendicular penetrations, each orientation persisting through several clear advances of the electrode, suggesting a set of discrete columnar subdivisions. The possibility of some kind of continuous variation in orientation with horizontal distance along the cortex was not, however, completely ruled out. Occasionally a highly ordered sequence was broken by an abrupt large shift in orientation of up to 90°. Shifts in ocular dominance occurred roughly every 0.25–0.5 mm and were independent of orientation shifts. In multiple parallel penetrations spaced closer than about 250 μ the slopes of the orientation vs. track distance curves were almost the same; reconstruction of these penetrations indicated that the regions of constant orientation are parallel sheets. On crossing perpendicular to these sheets, a total orientation shift of 180° took place over a distance of 0.5–1.0 mm. Column thickness, size of shifts in orientation, and the rate of change of orientation with distance along the cortex seemed to be independent of eccentricity, at least between 2° and 15° from the fovea. A few penetrations made in area 17 of the cat and in area 18 of the monkey showed similar orderly sequences of receptive‐field orientation shifts.