bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional and morphological studies of peptide‐containing neuroendocrine cells in goldfish hypothalamus
Authors: Reaves Troy Albert , Hayward James N. 
Published: January 2005

AbstractWe report the development of a double‐label method which combines intracellular recording, dye‐marking, and immunocytochemistry for the study of functional and morphological aspects of peptide‐containing neurons in the magnocellular preoptic nucleus of the goldfish hypothalamus. Using multiple techniques, we distinguish three types of peptide‐containing neurons: enkephalin (27%), isotocin (49%), and vasotocin (24%). Drawings of serial sections containing the dye‐injected cells were the basis for subsequent reconstruction. These peptidecontaining cells measure 14‐56 μm in somata diameter, are unipolar, bipolar, or multipolar in somata shape and lie 6–244 μm from the ependymal lining of the preoptic recess of the third ventricle. Their electrophysiological properties match those of other mammalian and fish magnocellular neuroendocrine cells. This report confirms the one neuron, one hormone (peptide) hypothesis, supports synaptic over electrotonic coupling between peptidergic and adjacent hypothalamic neurons, and suggests that chemical and functional classification of single electrophysiologically and neuroanatomically studied central neurons is feasible technologically.
Fine structure of rat locus coeruleus
Authors: Groves Philip M. , Wilson Charles J. 
Published: January 2005

AbstractLocus coeruleus of the rat was studied in material prepared by aldehyde‐osmium fixation. Cell bodies of locus coeruleus neurons possess large nuclei with a prominent nucleolus, a homogeneous karyoplasm of moderate density, and occasional indentations of the nuclear membrane. The cytoplasm is rich in organelles, including an extensive network of endoplasmic reticulum which forms well organized Nissl bodies. The highly developed Golgi apparatus surrounds the nucleus and extends into large dendritic trunks. In coronal section, cell bodies appear elongated along an approximate dorso‐ventral axis, and most dendrites as well as axons appear in cross‐section. In parasagittal sections the cells are very elongate, with dendrites and axons in the neuropil mostly cut longitudinally. Thus, locus coeruleus neurons possess disc‐shaped dendritic fields parallel to the anterior‐posterior axis of the brainstem, with predominantly longitudinal axo‐dendritic synaptic configurations.Presynaptic profiles in locus coeruleus neuropil were classified according to the characteristics of their vesicle populations and other features. The most frequently encountered synaptic ending was characterized by small, round, densely packed synaptic vesicles, and comprised approximately 41% of the total sample of 775 synapses. Another group having large, rounded synaptic vesicles, which could be traced in a number of instances to large myelinated axons, accounted for 20% of the sample. Synaptic endings having large, flattened vesicles were also numerous, comprising 23% of the total. Another category of presynaptic endings was identified as those possessing numerous, small, flattened vesicles and comprising about 11% of the sample. Presynaptic endings having many vesicles of mixed sizes accounted for 2% of the total, and another group of the same proportion having small, rounded synaptic vesicles but also an unusually large number of larger, dense‐cored vesicles was also present. Two other categories of synaptic endings were encountered, each comprising less than 1% of the total. One of these was derived from small, unmyelinated axons and contained clusters of pleomorphic synaptic vesicles. The other consisted of dendro‐dendritic synapses between locus coeruleus neurons and also displayed small clusters of pleomorphic synaptic vesicles near the zone of synaptic apposition. Quantitative analysis revealed that most afferents to the nucleus synapse onto dendrites ranging between 0.5 and 2.5 micrometers in diameter and onto spine‐like appendages derived from somata and dendrites. There were no significant differences between different categories of afferent terminals and their spatial distribution onto various postsynaptic targets of locus coeruleus neurons.
Monoaminergic presynaptic axons and dendrites in rat locus coeruleus seen in reconstructions of serial sections
Authors: Groves Philip M. , Wilson Charles J. 
Published: January 2005

AbstractLocus coeruleus was studied in rats pretreated with intraventricularly administered 5‐hydroxydopamine ½ to 3 hours prior to conventional aldehydeosmium fixation. Presynaptic profiles in locus coeruleus neuropil were classified according to the characteristics of their vesicle populations and other features, as in our previous report. Similar categories of endings were observed, and the sites of postsynaptic innervation were identical to those described previously, that is, a majority of synapses were made with dendrites between 0.5 and 2.5 micrometers in cross‐sectional diameter, a significant proportion was seen ending onto somatic and dendritic spines, with a relative paucity of synapses made with spine‐free membrane of somata and large dendritic trunks. There were no significant differences between different morphological categories of afferent terminals and their spatial distribution onto various postsynaptic targets on locus coeruleus neurons.In addition to various membrane‐bound compartments of the cytoplasm, three categories of synaptic endings were labelled by the synaptic marker, while all others were unlabelled. One of these was identified previously as containing small, rounded synaptic vesicles and an unusually large number of large, dense core vesicles. The synaptic vesicles were lightly labelled with scattered, small, eccentrically placed opaque cores inside the synaptic vesicles, apparently randomly distributed throughout the terminal. This terminal is thought to be serotonergic. A second category of labelled synapse has been previously identified as that derived from small, unmyelinated axons having clusters of pleomorphic synaptic vesicles in which the vesicles are heavily labelled by 5‐hydroxydopamine. These are believed to represent catecholaminergic synaptic endings derived from recurrent collaterals as well as extrinsic catecholaminergic innervation of locus coeruleus. A final category of heavily labelled profile was identified as presynaptic dendrites, which, along with recurrent catecholaminergic axon collaterals, probably play an important part in the intrinsic regulation of nucleus locus coeruleus. When 59 labelled synapses were examined in adjacent serial sections, every vesiclecontaining profile was associated with a synaptic contact having characteristic membrane specializations. A similar result was obtained when 132 other unlabelled terminals of different categories were examined in serial sections.
A stereological analysis of the cerebellar granule and purkinje cells of 30‐day‐old and adult rats undernourished during early postnatal life
Authors: Bedi K. S. , Hall R. , Davies C. A. , Dobbing J. 
Published: January 2005

AbstractMale rats undernourished from birth to 30 days of age were nutritionally rehabilitated till 160 days of age. Quantitative stereological procedures at the light microscope level were used to estimate, among other things, the numerical densities of cerebellar granule and Purkinje cells on a “per unit volume of cortex” basis. These were subsequently used to calculate granule‐to‐Purkinje cell ratios.The 30‐day‐old undernourished rats had a mean ± S.E. of 290 ± 27 granule cells for every Purkinje cell present, compared to 395 ± 34 for the controls. This was a deficit of about 27% (p<0.05). At 160 days of age, the previously undernourished rats still showed a persisting deficit of about 25% (p<0.05) in this ratio, despite the lengthy nutritional rehabilitation. There were no statistically significant age‐related changes in this ratio.The numerical density of Purkinje cells but not that of granule cells, was significantly greater in the previously undernourished rats than in controls, for both age groups. Increasing age caused a fall in the numerical density of both cell types.Granule and Purkinje cell nuclear diameters were unaffected by nutrition. However, Purkinje cell nuclei decreased in size by between 7%–13% with increasing age.These results indicate that undernutrition during early life can cause a permanent distortion of the relative number of the various cell types in the cerebellum.
Development of the brain stem in the rat. I. Thymidine‐radiographic study of the time of origin of neurons of the lower medulla
Authors: Altman Joseph , Bayer Shirley A. 
Published: January 2005

AbstractGroups of pregnant rats were injected with two successive daily doses of 3H‐thymidine from gestational days 12 and 13 (E12+13) until the day before birth (E21+22). In adult progeny of the injected rats the proportion of neurons generated on specific days was determined quantitatively in the major nuclei of the lower medulla. The earliest generated cells form two motor nuclei: the hypoglossal and dorsal vagal nuclei. The bulk of hypoglossal neurons are produced on day E12, with a small proportion earlier; the bulk of dorsal vagal neurons are produced, likewise, on day E12, with a small proportion on day E13. The neurons of the third motor nucleus of the region, the ambiguus, are generated later, with a peak on day E15. Neurons of the sensory relay nuclei, the gracilis, cuneatus, and solitarius are produced over a more extended period, with peaks on day E13; the exception was the external cuneate nucleus in which peak generation time was on day E15. In the caudal nucleus of the trigeminal complex, neurons of the subnucleus magnocellularis arise earliest, with a peak on day E14, and those of the subnucleus marginalis last, with a peak on day E15, and extending into day E16. The neurons of the nuclei raphe pallidus and obscurus, and of the dorsal and ventral portions of the caudal medullary reticular formation, are produced between days E12 and E15, without any obvious peaks. The neurons of the nucleus parasolitarius and the nucleus of Roller are produced relatively late, and the area postrema contains a germinal cell population throughout the embryonic period, presumably supplying cells to the choroid plexus of the fourth ventricle. On the basis of absolute datings, duration of neuron production, intranuclear and internuclear gradients, and other criteria, it is postulated that the neurons of the lower medulla are derived from at least eight different cytogenetic zones.
Development and degeneration of retina in rds mutant mice: Light microscopy
Authors: Sanyal S. , De Ruiter A. , Hawkins R. K. 
Published: January 2005

AbstractChanges during the development and degeneration of the retina in 020/A mice, which are homozygous for the newly reported rds (retinal degeneration slow), gene were studied by histological and enzyme‐histochemical methods with Balb/c mice carrying the normal allele as control. During normal development the total thickness of the retina grows from the time of birth till the age of 21 days and thereafter gradually diminishes, while the thicknesses of the component layers show a characteristic and differential change in course of their histogenesis. In the normal retina the perikarya of the cones are more frequent in the central than in the peripheral areas. The cone frequency in the central retina, but not in the periphery, increases with age and implies selective loss of rod cells in older animals.In the homozygous rds mice, the receptor layer remains rudimentary, but the other retinal layers show a normal trend of growth during the first 2 weeks after birth. Thereafter the morphological layers containing visual cell structures—the receptor, the outer nuclear, and the outer plexiform layers—begin to reduce. The loss of visual cells is readily marked by the reduction of the outer nuclear layer and is first evident at 2 weeks after birth. Degeneration is more rapid up to the age of 2–3 months, when the outer nuclear layer is reduced to half of its original thickness; thereafter degeneration progresses more slowly. The receptor and the outer plexiform layers are also simultaneously reduced. At 9 months, the peripheral parts of the retina, and at 12 months, the entire retina is completely lacking in visual cells. In the central retina of the mutant, rod and cone cell populations are equally affected up to the age of 6 months, as their relative frequency remains similar to the normal. In the peripheral retina, where cell loss is more pronounced, and in the central retina at 9 months an increase in relative frequency of cones is recorded and indicate increased susceptibility of the rods to later degenerative changes. The inner parts of the retina, including inner nuclear, inner plexiform, and ganglion cell layers, remain morphologically unaffected until irregular vascularization follows total loss of visual cells. The pigment epithelium is also affected at this late stage and appears depleted and patchy.In the normal retina, macrophages which are positively stained for the enzyme N‐acetyl‐β‐glucosaminidase appear in the inner layers with the growth of the retinal vasculature. In the mutant, increased frequency and stainability of the macrophages are discernible in the inner retina at 11 days. The macrophages migrate outwards and are observed in the outer nuclear layer and in the optic ventricle during the period of degeneration.These findings are compared with the observations in the other retinal degeneration mutants in rodents, and in retinitis pigmentosa in humans. The suitability of the rds mice as an animal model system for the human disease is emphasized.
Interhemispheric connections of visual cortex in the owl monkey, Aotus trivirgatus, and the bushbaby, Galago senegalensis
Authors: Newsome William T. , Allman John M. 
Published: January 2005

AbstractAnatomical techniques have been used to map within visual cortex the pattern of degenerating axonal terminals produced by surgical section of the splenium of the corpus callosum in the owl monkey, Aotus trivirgatus, and the bushbaby, Galago senegalensis. Previous studies in other species have shown that callosal inputs terminate preferentially in regions where the vertical meridian of the visual field is represented. Such a correspondence can serve as a useful aid for locating the boundaries of visual areas. The goals of this study have been (1) to assess the degree of correspondence between callosal inputs and previously identified vertical meridian representations in the owl monkey and bushbaby, and (2) to gain information from the pattern of callosal inputs concerning the existence and organization of as yet unidentified extrastriate visual areas. In both the owl monkey and the bushbaby, a discrete band of degenerating axonal terminals corresponds precisely to the vertical meridian representation at the V1‐V2 border, and a less precise increase in the density of degenerating axonal terminals corresponds to the vertical meridian representation of extrastriate area MT. A well‐defined band of degeneration on the ventral surface of the owl monkey's cerebral hemisphere corresponds to a previously unknown vertical meridian representation which is shared by two newly identified extrastriate visual areas. Elsewhere in visual cortex the pattern of callosal connections is more complex. Although this pattern may still reflect visual topography, it is not immediately useful for distinguishing areal boundaries.
The paraventricular nucleus of the hypothalamus: Cytoarchitectonic subdivisions and organization of projections to the pituitary, dorsal vagal complex, and spinal cord as demonstrated by retrograde fluorescence double‐labeling methods
Authors: Swanson L. W. , Kuypers H. G. J. M. 
Published: January 2005

AbstractExperiments using two retrogradely transported fluorescent dyes (bisbenzimide‐true blue, and Evans blue‐granular blue) were performed in order to determine whether the same or different populations of neurons in the paraventricular nucleus of the hypothalamus (PVH) project to the pituitary gland, dorsal vagal complex, and spinal cord in the rat. The results suggest that cells projecting to the pituitary gland are concentrated in the magnocellular core of the nucleus, while the descending connections arise primarily from the surrounding parvocellular division. The occurrence of neurons double‐labeled with both dyes further indicate that at least 10–15% of the labeled cells in the parvocellular division send divergent axon collaterals to the dorsal vagal complex and to the spinal cord. Cell counts suggest that at least 1,500 cells in the PVH project to the medulla and/or spinal cord. These results, combined with a cytoarchitectonic analysis, show that the PVH consists of eight distinct subdivisions, three magnocellular and five parvocellular. The lateral hypothalamic area and zona incerta also contain a large number of cells projecting to the dorsomedial medulla and spinal cord; approximately 15% of such cells are double‐labeled following injections of separate tracers into these two regions of the same animal.
The efferent projections of the central nucleus and the pericentral nucleus of the inferior collculus in the cat
Authors: Anderse Richard A. , Roth G. Linn , Aitkin Lindsay M. , Merzenich Michael M. 
Published: January 2005

AbstractThe efferent projections of the central nucleus of the inferior colliculus (ICC) and the pericentral nucleus of the inferior colliculus (ICP) were examined by placing restricted injections of anterograde tracers at electrophysiologically defined loci in the inferior colliculus (IC) of the cat.It was found that single loci in the ICC projected bilaterally onto the ventral division of the medial geniculate body (MGB) in the form of caudorostrally oriented sheets of terminals. The ICC loci also projected bilaterally onto the MGB In the form of caudorostrally oriented columns of terminals; these columns had their caudal aspects located in the medial division and their rostral aspect of the sheets of terminals in the ventral division was folded and passed though both pars lateralis and pars ovoidea of the ventral division. Every component of the ICC‐to‐MGB projection was cochleotopically ordered. Periodic discontinuties of two types were noted in the projections of the ICC onto pars lateralis (VI) of the ventral division. The on type of periodic discontinuity sometimes approximated bands oriented caudorostrally in the caudal aspect of VI. The second type of discontinuity was of very thin parallel columns of more intense Labeling oriented roughly discontinuity and oblique or normal to the first type of discontinuity.Injections in the ICP produced autoradiographic labeling in the caudal dorsal nucleus (Dc) of the dorsal division of the MGB. Thus the ICC‐to‐MGB and ICP‐to‐MGB projection are segregated.The efferent connections of the IC with other brainstem auditory structures were noted.
Non‐specific esterase activity in reactive cells in injured nervous tissue labeled with 3H‐Thymidine or 125Iododeoxyuridine injected before injury
Authors: Schelper Robert L. , Adrian Erle K. 
Published: January 2005

AbstractTritiated thymidine (3H‐TdR) injected before a stab wound of the spinal cord or transection of the hypoglossal nerve has resulted in many labeled reactive cells in the CNS after injury, most of which have the ultrastructural features of microglia. To test for the possible origin of these labeled cells from monocytes, we examined them for the presence of sodium, fluoride‐ (NaF) sensitive non‐specific esterase (NSE), an enzyme characteristic of monocytes. Some of the labeled cells in stab wounds had NaF‐sensitive NSE, but no such cells were found in the nucleus of the injured hypoglossal nerve. To test for the possibility that the NSE‐negative labeled cells had been labeled by reutilization of 3H‐TdR, we used 125I‐5‐iodo‐2'deoxyuridine (125I‐UdR), a thymidine analogue with a much lower rate or reutilization, to label blood mononuclear cells prior to either a spinal cord stab wound or hypoglossal axotomy. The number of labeled cells was decreased in the spinal cord wound, but more than half were NSE‐negative. No labeled blood mononuclear cells were found in the hypoglossal nucleus, although there was no decrease in the hyperplasia of unlabeled non‐neuronal cells. When 125I‐UdR was injected on the fourth day after hypoglossal axotomy, or when both 3H‐TdR and 125I‐RdR were injected simultaneously before hypoglossal axotomy, many labeled cells were found in the hypoglosaal nucleus, indicating that 125I‐UdR can be used by the reactive cells and that it did not inhibit their proliferation. Therefore, the microglial cells that proliferate in response to peripheral nerve injury are not recently derived from any type of circulating large blood mononuclear cell. The most likely explanation for the presence of the 3H‐TdR‐labeled cells in the nucleus of the injured hypoglossal nerve in that they were proliferating intrinsic labeled by reutilization of 3H‐TdR.
Development of the mossy fibers of the dentate gyrus: I. A light and electron microscopic study of the mossy fibers and their expansions
Authors: Amaral David G. , Dent Judith A. 
Published: January 2005

AbstractThe postnatal development of the axons of the dentate granule cells—the so‐called mossy fibers—was studied at the light microscopic level in Timm and Golgi preparations and also by transmission electron microscopy. In the Timm‐stained material, there was a distinctive coloration in the hilus and incipient stratum lucidum, indicating the presence of mossy fibers, on the first postnatal day. Over the next two weeks, the stained areas became more extensive, the size and density of the stained particles increased, and the particles became more intensely stained. These signs of progressive development of the mossy fibers appeared to reflect, temporally and topographically, the developmental gradients followed by their parent granule cells.The Golgi material confirmed the presence of mossy fibers in the hilus on the first postnatal day. Fasciculi of mossy fibers were observed in the stratum lucidum of the 3‐day‐old hippocampus, and although these immature axons were devoid of large synaptic expansions, they did have prominent growth cones at their termini. Small expansions along the lengths of the axons first appeared on day 7 and these grew to approximately an adult size and complexity by about day 14. The postsynaptic component of the mossy fiber synapse, the “thorny excrescence,” did not begin to emerge from the proximal portion of the pyramidal cell dendrites until sometime after day 9.At the electron microscopic level we observed, on the first postnatal day, small, immature mossy fiber expansions which made both symmetric and asymmetric contacts directly with dendritic shafts. These profiles, which were only one tenth the size of mature expansions, grew rapidly between postnatal days 1 and 9 and increased their mean area by a factor of five. On or about day 9, as the “thorny excrescences” emerged, the asymmetric synapses came to be associated with these spinous processes.Taken together, the Golgi and electron microscopic analyses support the suggestion that mossy fibers establish synaptic contact with pyramidal cell dendrites early in the postnatal period, several days before there is any indication of spine development. Furthermore, the “thorny excrescences” develop after the more typical, pedicellate spines have appeared on the distal pyramidal cell dendrites. Finally, while it is clear that the mossy fibers in our 21‐day‐old material are, for the most part, fully matured, a more subtle and protracted development of the system, long into adulthood, is indicated by the increased area and density of stained particles in the Timm preparations from adult animals.