bluuebunny/crossref_metadata_2025_split huggingface dataset:
Types and distribution of synapses upon basket and stellate cells of the mouse cerebellum: An electron microscopic study
Authors: Lemkey‐Johnston N. , Larramendi L. M. H. 
Published: January 2005

AbstractThe consistent identification of nerve terminals in the molecular layer of the mouse cerebellum has permitted electron microscopic study of the spatial and numerical distribution of synapses upon the soma and dendrites of stellate cells at three depths in the molecular layer.The number of boutons synapsing per 100 μ of cell perimeter, or general synaptic density (G.S.D.) has been found to vary among stellate cells located at different depths in the molecular layer. It has also been found that the G.S.D. of the dendrites is greater than that of the cell bodies of these cells.The specific synaptic densities, or number of boutons of specific type (such as parallel fiber, climbing fiber etc.) synapsing upon 100 μ of cell perimeter, have been found to vary significantly for each type of terminal among upper, lower, and very low stellate cells in the molecular layer. Very low stellate cells receive almost exclusively Purkinje collateral synapses upon their cell bodies (the dendrites have not been identified) whereas low stellate cells (basket cells) receive upon both their cell bodies and dendrites mostly parallel fiber synapses and in decreasing order lesser amounts of basket‐stellate, Purkinje collateral and climbing fibers. Uppermost stellate cells, however, receive only parallel fiber and a few stellate terminals.The distribution of synapses upon stellate cells found in the mouse agrees with physiological data reported in the cat.
Morphology of the regenerated spinal cord in the lizard, Anolis carolinensis
Authors: Simpson Sidney B. 
Published: January 2005

AbstractThe regenerated spinal cord of the lizard, Anolis, was studied with the aid of the light and electron microscopy. The regenerated cord consists of an ependymal epithelium, descending central nerve fibers and the connective tissue of meninges. The ependymal tube is a discrete entity and is separated from the surrounding connective tissue by a basement lamina. The ependymal tube is composed of a morphologically homogeneous epithelial cell population. The ependymal cell itself fits closely the previous descriptions of the ependymal tanycyte.The majority of the regenerated central nerve fibers are contained within the ependymal tube and are fasciculated in longitudinal rows between the basal processes of adjacent ependyma cells. This association of regenerated central fibers and the ependymal tube and its relation to guidance of intercentral fiber regeneration is discussed.
Lateral‐line organs in some teleosts: Cirrhina mrigala ham. Buch. (Cyprinidae), Ophicephalus (Channa) punctatus Bloch (Channidae) and Gobius striatus Day (Gobiidae)
Authors: Srivastava C. B. L. , Srivastava M. D. L. 
Published: January 2005

AbstractThe structure and location of “ordinary” lateral‐line organs of the fry and the adult specimens of three teleosts, Cirrhina mrigala, Ophicephalus (Channa) punctatus and Gobius striatus, have been studied and the results have been discussed. The stalked condition of surface organs, described for G. striatus, is a new feature reported for the first time in this communication. An attempt has been made to classify “ordinary” lateral‐line organs on morphological grounds, especially the group of “pit organs,” taking into consideration the orientation of the neuromast concerned in relation to the surface of the adjacent skin, the basement membrane, the dermis and the thickness of the surrounding epidermis.
The dermatomes of the sheep
Authors: Kirk Edwin J. 
Published: January 2005

AbstractThe dermatomes of the sheep, first cervical through second coccygeal were isolated by the method of “remaining sensibility” and defined by mapping the areas of residual sensitivity to pinching of the skin with fine‐pointed forceps.The disposition of these dermatomes was similar to that in other species, but appreciable variations between individual sheep were common. The trunk fields extended between the dorsal and ventral midlines of the body as regular, continuous, serial bands. They showed a cranio‐caudal overlap of approximately one‐half, but only slight overlapping across the dorsal and ventral midlines.Most of the limb fields reached the dorsal midline of the body, and in both the fore and hind limbs three dermatomes extended to the digits. A close correlation existed between the forelimb dermatomes and those of other species: a less precise correlation was found in the hindlimb. The abrupt flexures in the borders of some limb fields appear to have been produced by the considerable reduction from the primitive pentadactyl condition.The cutaneous sensory areas supplied by the three main divisions of the trigeminal (fifth cranial) nerve were also charted. Their disposition was again similar to that in other species, and the overlap between them much less than that of the dermatomes.
A single unit analysis of trigeminal projections to bulbar reticular muclei of the rat
Authors: Nord Samuel G. , Kyler Harry J. 
Published: January 2005

AbstractThe lateral bulbar reticular formation of anesthetized rats was explored with microelectrodes in order to compare the response and field characteristics of its somatosensory cells with properties of units located in the adjacent spinal trigeminal complex. Responses were evoked in the cells using natural and electrical stimulation of the skin. Neurons in the reticular nuclei tended to exihibit long latencies, low folowing capacities and large receptive fields. On the other hand, trigeminal complex cells generally revealed opposite characteristics, more typical of primary sensory structures, such as short latencies, high following capacities and punctate‐to‐small fields. The distinction between the regions was emphasized by additional qualities which were peculiar to the reticular neurons: Bilateral peripheral representation, into very coarse mechnical stimulation. In amny respects, the data indicate that the lateral reticular formation is intimately involved in the mediation of facial pain. They also support the view that it participated in this function by regulating the flow of nocioceptive activity from receptive mechanisms of the skin to the lemniscal pathway.
Synaptic analysis of inner plexiform layer in human retina
Authors: Foos Robert Y. , Miyamasu Walter 
Published: January 2005

AbstractAn ultrastructural synaptic analysis based on observations from 33 serial thin‐sections of the inner plexiform layer in a volume sample of midperipheral human retina is presented. Of the 152 identifiable neuronal processes 7lpar;total 187) 14 were bipolar, 112 amacrine, and 26 ganglion. One hundred and forty‐seven synapses were present — 31 bipolar (ribbon) and 116 amacrine (conventional). The ribbon synapses were divided on the basis of their postsynaptic processes into: amacrine, ganglion (16); amacrine, amacrine, ganglion (9) amacrine, amacrine (3) amacrine, amacrine, amacrine (1) ganglion (2), both incomplete in sections(. Of the 116 conventional synapses, 28% were amacrine‐bipolar, 34% amacrine‐amacrine and 38% were amacrine‐ganglion. The occurrence of extra amacrine process(es) and the occasional absence of a ganglion cell dendrite at bipolar (ribbon) synapses, as well as the relative abundance of amacrine‐amacrine (conventional) synapses, suggests a relatively greater role of amacrine cells in mediating visual transformations in the midperipheral human retina than has been described previously.
Kinetics of proliferation and latency between final cell division and onset of differentiation of cerebellar stellate and basket neurons
Authors: Rakic Pasko 
Published: January 2005

AbstractThymidine‐3 autoradiographic, Golgi, and electonmicroscopic methods were combined to analyze proliferation kinetics and to determine the interval between final cell division and initial differentiation of interneurons of the cerebellar molecular layer (stellate and basket cells). The protracted span of development makes rhesus monkeys particularly suitable for unravelling temporal sequences in neurogenesis. Labeling index measurements in autoradiograms of adult animals injected at different developmental ages indicate that interneurons are generated at a steady rate of about 1% per day from the eightieth embryonic day to just after birth. The precursor pool is about 300,000 cells, each yielding on the average one differentiating and one proliferating daughter cell. The rate of interneuron proliferation parallels neither the exponential production of granule cells nor the 40‐fold expansion of cerebellar surface.Adult position of interneurons correlates with time of cell origin; the deep cells are generated first, the more superficial ones progressively later. By comparison of autoradiographic maps with Golgi impregnations and electronmicrographs at developmental stages, the interval from final mitosis to dendritic outgrowth and onset of synaptogenesis was found to increase systematically, reaching a maximum of two months for the last‐forming interneurons. Postmitotic interneurons, as yet without dendrites, accumulate at the interface between the external granular layer and the thickening molecular layer, and only later become enveloped by newly‐forming processes of other cells. Identified among these were mainly parallel fibers, some climbing fibers, axons of previously generated interneurons, and Purkinje dendrites. It is speculated that any or all of these may induce interneuron differentiation, since proliferation of any given interneuron is completed relatively early while it differentiates only later when its local milieu has developed.
Fluorescence histochemistry of monoamine‐containing cell bodies in the brain stem of the squirrel monkey (Saimiri sciureus). The locus caeruleus
Authors: Hubbard Jack E. , di Carlo Vincenzo 
Published: January 2005

AbstractA study of the locus caeruleus is presented as the first in a series of papers describing the monoamine‐containing cell bodies in the brain stem of the squirrel monkey (Saimiri sciureus) using the fluorescent histochemical technique. Found most caudally in the roof of the ventriculus quartus, the locus caeruleus attains its greatest density of cell bodies medial to the tractus mesencephalicus n. trigemini at the level where the tract lies medial and ventral to the brachium conjunctivum. More rostrally, the cells are found dorsal, medial, and ventral to the brachium conjunctivum. Finally, in a location to a few cells closely associated with the fibers of the nervus trochlearis. Careful examination of closely packed cells medial to the tractus mesencephalicus n. trigemini reveals that almost all of the cell bodies of this region fluoresce, thus displaying a positive reaction for monoamines. On the basis of the fluorescent histochemical technique, therefore, the authors conclude that this region which often is indicated in the literature as the nucleus tr. mesenceph. n. trigemini is actually composed of the catecholamine‐containing cells of the locus caeruleus.
Time of origin of corresponding cell classes in the cerebral cortex of normal and reeler mutant mice: An autoradiographic analysis
Authors: Caviness V. S. , Sidman R. L. 
Published: January 2005

AbstractReeler, a recessive mutation in mice, causes cytoarchitectonic abnormalities of the cerebral and cerebellar cortices. Although the relative positions of classes of cells in the cerebral cortex are markedly abnormal, the time of origin of cells in each class appears to be normal by autoradiographic criteria. In the retrohippocampal cortical structures and in the adjacent neocortex, the earliest generated cell class, the polymorphic, arises at the same embryonic time in normal and reeler littermates. Whereas these cells come to form the deepest stratum of the normal cortex, they lie in an immediately subpial position in the mutant, there being no cell‐sparse external plexiform (molecular) layer. A population of larger cells is generated next; these normally come to lie in more superficial layers but instead lie deep to the polymorphic cells in the mutant. Granule cells of the neocortex arise last, simultaneously in normal and reeler; they form the most superficial neocortical cell stratum in the normal, but lie at a more restricted level within the large cell zone in the mutant. These data indicate that the cytoarchitectonic anomaly in reeler is independent of the spatiotemporal program of cell generation. It appears likely that the reeler genetic locus governs embryonic events, as yet undefined, that direct the postmitotic migrating young neuron to class‐specific levels within the cortex.
A morphological investigation of an early reflex pathway in developing rat spinal cord
Authors: Vaughn James E. , Grieshaber Judith A. 
Published: January 2005

AbstractThe early development of the disynaptic cutaneous reflex pathway in the brachial spinal cord of rat fetuses was investigated both light and electron microscopically. The spinal cord areas which contain the neurons (association interneurons and lateral motor nucleus neurons) involved in this reflex pathway were identified in both neurofibrillar (silver‐stained) and semithin plastic embedded specimens. Equivalent areas were identified in adjacent ultrathin preparations for electron microscopy and micrographs of these sample areas were taken of specimens at embryonic days 13.5–19.5 as well as for postnatal day 4 and adult specimens. The relative volume of association and dorsolateral motor neuropils occupied by synaptic boutons in these micrographs was determined using stereological methods. The mean number of synaptic junctions and boutons per 100 μ2 was also determined for the two neuropil areas at each developmental stage. These analyses show that synaptic junctions and boutons occur in the dorsolateral motor neuropil before they can be found in association neuropil. Synapses within motor neuropil are first seen at embryonic day 13.5. Synaptogenesis in the dorsolateral motor neuropil is temporally correlated with the presence of numerous fibers which, in silver‐stained specimens, can be seen to arise from the association interneurons and to course into the dorsolateral aspects of the motor nucleus. Synaptic junctions and boutons are not observed in the association neuropil until embryonic day 14.5 and this correlates well with the time when collaterals of the primary afferent fibers can first be observed penetrating into the dorsal half of the intermediate zone from the anlage of the dorsal funiculus. The precocious development of synaptic junctions in dorsolateral motor neuropil in comparison to the association neuropil continues throughout the developmental period examined. These data support a retrograde pattern of synaptogenesis in the early development of the spinal cutaneous reflex pathway. Association interneurons make synaptic contacts with motor neurons before synapses are formed between primary sensory neurons and association cells. This sequence is the reverse of the normal flow of nerve impulses through spinal reflex pathways.
The distribution of rods and cones in the retina of the cat (Felis domesticus)
Authors: Steinberg Roy H. , Reid Miriam , Lacy Paula L. 
Published: January 2005

AbstractThe distribution of rods and cones in the cat retina was studied by light microscopy. The rods and cones were counted from the area centralis to the temporal periphery in photomicrographs of transverse sections through the inner segments. A 16% correction for the effect of tissue shrinkage was applied to the densities obtained in fixed‐dehydrated tissue, by comparing these counts with those obtained from similar retinal areas in fresh tissue.The cone distribution was characterized by a steep increase in cone density centrally, which was elongated in the nasotemporal axis, and coincided approximately with the central increase in ganglion cell density (Stone, '65). Cone density in the area centralis peaked at 26,000–27,000/mm2, and fell to a plateau of 4000/mm2 in the periphery and to less than 3000/mm2 near the ora serrata. The density of rods was greater than the density of cones in all regions. The rods reached a maximum density of 460,000/mm2 at an eccentricity of 10–15°, in a region which completely surrounded the central cone elevation. Centrally, the rod distribution was characterized by a sharp fall in density, reaching a low of 275,000/mm2 at the point of peak cone density. Peripherally, there was a plateau of high rod density at above 400,000/mm2, out to about 30° temporal eccentricity. Beyond this plateau, rod density steadily fell, and reached a low of 250,000/mm2 near the ora serrata. The rod/cone ratio reached a low value of 10.5–11.0 in the central region of maximum cone density. It then rose steeply to reach a plateau of about 65 in the periphery, while near the ora serrata there were 100 rods for each cone.The rods were arranged in well defined rows, and each rod was surrounded by six other rods. The cones were interspersed throughout the rod mosaic and were less regularly arranged than the rods. In fresh tissue, rod outer segment diameters ranged from 1.0 μ to 1.6 μ. rod diameters were smallest in the region of maximum rod density and increased, along with the decrease in rod density, both in the periphery and in the area centralis. Two thirds of the central decrease in rod density from the pericentral peak could not be accounted for by the increase in the percentage of space occupied by cones, and was consistent with a central increase in rod diameter.Receptor‐ganglion cell convergence was estimated by comparing receptor densities with the ganglion cell densities of Stone ('65). Cone‐ganglion cell convergence reached a minimum in the area centralis at the cone density peak, probably indicating the retinal region in which photopic acuity is at an optimum. Minimum rod‐ganglion cell convergence, as estimated from the rod/large ganglion cell ratio, reached a minimum at about 7.5° central to the peak of rod density, and at about the same eccentricity as the human scotopic acuity optimum.
Electron microscopy of non‐neuronal cellular changes accompanying neural degeneration in thalamic nuclei of the rabbit. II. Reactive elements within the neuropil
Authors: Matthews Murray A. , Kruger Lawrence 
Published: January 2005

AbstractSurgical destruction of the cortical projections of thalamic neurons results in rapid and profound atrophy of these neurons accompanied by a variety of non‐neuronal reactive changes. During the first post‐operative week, non‐neuronal elements, distinct from astrocytes and normal oligodendrocytes and tentatively designated as “M” cells, become evident in the degenerating thalamic nuclei. Some “M” cells are characterized by heterochromatin nuclei and numerous free ribosomes, and resemble the agranular leukocytes accumulating simultaneously within the perivascular space of small vessels coursing through these regions (Matthews and Kruger, '73). Examples of such cells were sometimes seen bridging the external basal lamina. Other “M” cells display many profiles of granular endoplasmic reticulum and fewer free ribosomes but cannot be precisely classified as to nature and possible source. From the second through fourteenth week, “M” cells increase in prominence and accumulate electronlucent lipid vacuoles and phosphotungstic acid (PTA) positive dense bodies, presumably lysosomes, until these enlarged lipid‐laden cells constitute the predominant non‐neuronal entities in the zone of degeneration, in addition to hypertrophied astrocytes. Thirty‐four weeks post‐operatively “M” cells have decreased in size and apparent numbers, and dense bodies display a lessened affinity for PTA in addition to morphologic patterns suggestive of terminal lysosomes. Normal light and dark oligodendrocytes are encountered within the zone of degeneration throughout the entire survival period.It is suggested that a significant proportion of “M” cells are of mesodermal (hematogenous; perivascular) origin although “M” cells display sufficient diversity of morphology to warrant consideration of additional sources for the reactive vacuolated forms. The experimental observations are discussed in relation to past and present concepts concerning the nature, origin and pathologic transformation of elements classified as microglia.
The effect of lid suture upon the growth of cells in the dorsal lateral geniculate nucleus of kittens
Authors: Guillery R. W. 
Published: January 2005

AbstractIt has been shown previously that unilateral suture of the eyelids of young kittens produces a reduced growth of cells in the visually deprived geniculate laminae (Wiesel and Hubel, '63). However, this effect is seen only in the parts of the lateral geniculate nucleus in which a binocular competition is possible. That is, where geniculate cells that receive from the deprived eye are aligned with cells that receive from the normal eye, the growth is affected. Where the geniculate cells that receive from the deprived eye are not aligned with any normally innervated cells, either because the deprived cells would normally receive from the monocular crescent of the visual field or because they lie opposite a part of the nucleus that has suffered degenerative changes, the cell growth is not affected (Guillery and Stelzner, '70; Guillery, '72).The above observations suggest that bilateral lid suture may have relatively little effect upon geniculate cell growth. Eight kittens have been raised with both eyelids sutured and the size of the geniculate cells in layers A and A1 measured. Comparison with measurements obtained from seven normal cats of the same age, shows that binocular lid suture has little, if any, effect upon geniculate cell growth.
Antennal sensory system of the cockroach, Periplaneta americana: Postembryonic development and morphology of the sense organs
Authors: Schafer Rollie , Sanchez Thomas V. 
Published: January 2005

AbstractAntennal growth in the cockroach, Periplaneta americana, takes place by division of the meriston (third antennal segment) and the meristal segments at the base of the antennal flagellum. Olfactory and contact chemoreceptive sense organs are the most numerous receptor organs on the antenna at all stages of postembryonic development. The sensory complement of male and female antennae is identical during the nymphal period, but a large difference between sexes appears at the adult stage. The adult male has nearly twice as many olfactory sensilla as the female, and more than half of these sensilla appear at the adult stage. These morphological data are consistent with the hypothesis that sensory receptors specific to the female sex attractant appear in the male only at the adult stage.
Congenitally abnormal visual pathways in mink (Mustela vison) with reduced retinal pigment
Authors: Sanderson K. J. , Guillery R. W. , Shackelford R. M. 
Published: January 2005

AbstractThe retinogeniculate pathways of several different genotypes of mink have been studied by the Nauta and Fink‐Heimer methods. An abnormal retinogeniculate pathway has been found in all mink in which the retinal pigment is reduced. Most of the abnormally routed nerve fibers arise in the temporal retina and cross in the chiasm, instead of staying ipsilateral as is normal. Some abnormal fibers in some of the mink also appear to arise in the nasal retina close to the line of decussation, and these pass ipsilaterally instead of following their normal crossed pathway.A lack of pigment in the coat is not by itself associated with a pathway abnormality. In general, the size of the abnormal fiber component is related to the severity of the retinal pigment deficit. The abnormality is not related specifically to one gene or gene combination. We have found eight different gene combinations which produce a reduction of retinal pigment associated with a pathway abnormality.