bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytology of neurons of the hypothalamic ventromedial nucleus in the adult male rat
Authors: Van Houten Mark , Brawer James R. 
Published: January 2005

AbstractRecent evidence suggests that the hypothalamic ventromedial nucleus contains a wide variety of functionally specialized neurons, some of which are located within discrete regions of the nucleus. However, regional morphologic variations in neuronal populations within the HVM have not been demonstrated. In the present report, the neurons of the HVM were studied in young adult, male rats with the electron microscope. The collection and analysis of cytologic data were systematized with reference to location on a histologic map of the HVM, which was prepared prior to fine structural study.Neurons of the HVM were observed to exhibit regional variations in cytology. For example, cisternae of the rough endoplasmic reticulum in the anterior and dorsomedial regions of the nucleus are commonly collected into regular stacks typical of Nissl bodies. In contrast, rough cisternae in the posterior ventrolateral region of the HVM are often extremely long and pleomorphic, and form broad, loosely organized Nissl zones, in which occur myelin figures and wide varieties of cytoplasmic filamentous bodies.Other neurons located principally in the ventrolateral and posterior regions of the nucleus are characterized by the presence of whorled bodies. Still others restricted to the lateral rim of the nucleus are conspicuous by virtue of their enormous size and massive accumulation of Nissl material.One extremely unusual variety of HVM neuron is distinguished by the presence of large, acristic mitochondria, polysomal disaggregation, and aberrant nucleolar morphology. These cytologic features may indicate metabolic quiescence and perhaps anaerobiosis.Possibly these region‐centered variations in neuronal cytology reflect the functional parcellation of the HVM.
A quantitative study of synaptic patterns in turtle visual cortex
Authors: Ebner Ford F. , Colonnier Marc 
Published: January 2005

AbstractThe distribution of different synaptic types has been analyzed quantitatively in the molecular and subcellular layers of turtle „vislual”︁ cortex. The density of vesicle‐containing‐profiles (VCPs) is 122.2/400 square μm in the molecular layer and 61.0/400 square μm in the subcellular layer. In both layers, approximately 85% of VCPs conatin round vesicles (RVCPs), 12%, flat vesicles (FVCPs) and 1%, dense core vesicles (DVCPs). Vacuolar invaginations (VIs) are not uncommon in the molecular layer (3.4%) but are rare in the subcellular layer (0.6%). Synaptic conatacts are formed in the plane of section by three out of ten RVCPs and FVCPs, while only one out of the 146 DVCPs sampled in this study was associated with a membrane differentiation. In the molecualr layer, the percentage distribution of the different subgroups of synaptic types is as follows: round‐asymmetrical contacts, 82.5% (77.5% on dendritic spines and 5.0% on dendritic shafts); round‐symmetrical contacts, 3.8% (2.3% on spines and 1.5% on shafts);flat‐symmetrical contacts, 13.1% (8.8% on shafts and 4.3% on spines; flatasymmetrical contacts 0.6% (0.4% on spines and 0.2% on shafts)). In the subcellular layer, the distribution is quite different: round‐asymmetrical contacts. 72.4% (38.6% on shafts and 33.8% on spines); round‐symmertical contacts, 12.8% (8.2% on shafts and 4.6% on spines); flat‐symmetrical contacts, 13.9% (9.3% on shafts and 4.6% on spines); flat‐asymmetrical contacts, 0.9% all on dendritic shafts. The density distribution of VCPs in the molecular layer changes with depth. RVCPs are fewer on the distal third of the apical dendrites, and most numerous in the middle third with a small dercease in number in th proximal third. FVCPs are more homogeneously distributed, perhaps increasing slightly in number towards the proximal parts of the dendritets. RVCPs are most numerous on dendritic spines. These spines are of two types whose relative number varies with depth. Large organelle‐filled spines predominate in the upper third while small „empty”︁ spines are most numerous in the lower third of the molecular layer.
Atlas of the distribution of monoamine‐containing nerve cell bodies in the brain stem of the cat
Authors: Poitras D. , Parent A. 
Published: January 2005

AbstractThe distribution and morphological characteristics of monoamine (MA)‐containing neuronal somata in the brain stem of kittens and of adult cats were studied by means of the Falck‐Hillarp histofluorescence method. This investigation has shown, among other things, that in the mibrain of the cat the catecholamine (CA) perikarya are chiefly confined to the pars compacta of the substantia nigra, the ventromedial tegmental area, the nucleus linearis rostralis and the nucleus parabrachialis pigmentosus. Numerous CA neurons are also present in the dorsolateral part of the pontine tegmentum but also within the nucleus subcoeruleus, in nuclei lemnisci lateralis dorsalis and in nuclei parabrachialis lateralis and medialis. In the medulla, a few CA neuronal somata are lying near the hypoglossal nucleus whereas a larger number of CA cell bodies occur at the level of nucleus reticularis lateralis and in nucleus paragigantocellularis lateralis. On the other hand, most of the serotonin (5‐HT) perikarya are confined to the raphe nuclei of the brain stem: nuclei raphe dorsalis, centralis superior, raphe pontis, raphe magnus, raphe pallidus and raphe obscurus. Some 5‐HT neuronal somata are also found lateral to the pyramidal tract and to the inferior olivary complex. The various similarities and differences in respect to the pattern of the topographical distribution of MA neurons in the brain stem of the cat as compared to that of other mammals are discussed.
Projections to the inferior olive of the cat II. Comparisons of input from the gracile, cuneate and the spinal trigeminal nuclel
Authors: Berkley K. J. , Hand P. J. 
Published: January 2005

AbstractThe present experiments compare the pojections to the inferior olive of the cat from the gracile, cuneate and spinal trigeminal nuclei. A differential labeling strategy was used for these comparisons.It was found that all three somatic sensory nuclei project to portions of all three major divisions of the contralateral inferior olive. The spinal trigeminal n. may also project less densely to the ipsilateral medial accessory olive. Projections to the dorsal accessory nucleus (DAO) and the medially‐adjacent ventral lamella of the principal nucleus are roughly somatotopically organized. Although there is considerable overlap between the projections predominantly to medial DAO, and the spinal trigeminal nucleus pars caudalis projects predominantly to the most medial portions of DAO and the ventral lamella of principal olive. Projections to the medial accessory olive, on the other hand, are not as highly organized. Instead, they overlap extensively within a small eggshaped area in the middle of the caudal half of the nucleus.Whereas all portions of the gracile and cuneate nuclei project to the inferior olive, only the pars caudalis of the spinal trigeminal nucleus appears to do so.These results were compared with the three available olivocerebellar maps as well as with the available behavioral and electrophysiological evidence on cerebellar somatotopic organization. This comparison indicated that the inputs to the cerebellum from the three second‐order somatosensory nuclei via the inferior olive appear to be generally consistent with cerebellar somatotopic organization. This consistency is apparent not only with respect to the longitudinally‐organized, vermal and paravermal differences in the anterior lobe, but also with respect to the transversely‐organized specific somatotopy of the intermediate zone of the anterior lobe and the paramedian lobule.
In situ injection of kainic acid: A new method for selectively lesioning neuronal cell bodies while sparing axons of passage
Authors: Coyle Joseph T. , Molliver Mark E. , Kuhar Michael J. 
Published: January 2005

AbstractThe morphologic sequelae following stereotaxic injection into the rat striatum of kainic acid, a conformationally restricted analogue of glutamate, were examined by means of bright fields, histofluorescence and electron microscopic techniques. The neuropathologic response to kainate injection occurs in two distinct phases. Fist, the intrinsic neurons of the striatum undergo a rapid degeneration during the first 48 hours after injection; this is characterized by the sequential loss of cytoplasmic Nissl‐substance (chromatolysis), shrinkage of the perikarya, clumping of the nuclear chromatin and finally disruption of the nuclear membrane. Between one and three weeks after injection, a marked proliferation of astrocytes in the gray matter formerly populated by neurons characterizes the second phase. The region of several neuronal loss in the kainate injected stratum is approximately spherical in shape, and its extent is non‐linearly related to the amount of kainate injected. The neuropil of the injected striatum is markedly disrupted due to the death of intrinsic neurons and loss of their processes. Yet, histofluoresence microscopy demonstrates that the dopaminergic axons projecting from the substantia nigra do not degenerate in the kainate injected striatum; electron microscopic studies indicate that corticofugal fibers traversing the striatum also unaffected by kainate. Many presynaptic boutons, presumably of extrinsic origin, are intact up to ten days after injection; osmophilic vestiges of postsynaptic elements remain adherent to these boutons. Numerous phagocytic astrocytes are observed throughout the lesioned area. These morphologic studies provide (direct) evidence that in situ injection of kainic acid in brain causes a selective degeneration of neurons with cell bodies in the area of the injection but spares axons that arise from perikarya outside the region but pass through or terminate in the injected area. Thus, in situ injection of kainic acid is a new technique for making selective brain lesions that will be useful for examining neuronal connectivity.
Terminal proliferation and synaptogenesis following partial deafferentation: The reinnervation of the inner molecular layer of the dentate gyrus following removal of its commissural afferents
Authors: McWilliams Randall , Lynch Gary 
Published: January 2005

AbstractThe inner one‐third of the dendritic region of the dentate gyrus granule cells in adult rats receives projections primarily from the commissural fibers of the contralateral hippocampus and the associational fibers of the ipsilateral hippocampus. At two to four days following the complete removal of the contralateral hippocampus, approximately 25% of the terminals in the inner molecular layer are observed degenerating. This provides an excellent model system to investigate possible terminal proliferation induced by deafferentation since (1) the experimental lesion is easily reproducible, (2) no retrograde reactions occur in the granule cells as a direct result of the lesion, (3) no shrinkage is detected in this region following commissural deafferentation, (4) the same dendritic region can be relocated precisely in each animal, and (5) the synaptic counts are highly consistent between animals.Results from this study and from previous investigations demonstrate that the commissural projection is contained within a 0–80 μ zone directly above the granule cell layer. Complete photomontages of this zone were taken, but only the 40–80 μ zone was quantified for neuronal and glial changes in three normal, five 2‐ to 4‐day, and five 50‐ to 75‐day postlesion animals. The average synaptic count dropped to 64% of control values by 2 to 4 days, but returned to 97% by 50‐ to 75 days postlesion. The number of terminals showing multiple synaptic contacts increased slightly in the long‐term animals. Measurements of average terminal area showed no change between the short‐ and long‐term survival groups. These results indicate that this dendritic region is reinnervated following partial deafferentation and that the reinnervation is due primarily to the formation of new terminals rather than the expansion of pre‐existing terminals.
Functional properties of the corticotectal projection in the golden hamster
Authors: Rhoades Robert W. , Chalupa Leo M. 
Published: January 2005

AbstractApproximately 31% of the cells recorded in the hamster's superior colliculus could be activated by stimulation of the ipsilateral primary visual cortex. While cortically activated cells were encountered in all laminae of the colliculus where visual cells were isolated, the highest probability of driving visual cells was observed in the deeper laminae, that is, those ventral to the stratum opticum. Response latency, jitter (latency variability), latency shifts as a function of shock intensity, thresholds, and spike numbers did not vary as a function of depth in the colliculus. There was a clear correspondence between the visual fields of the best cortical stimulus points and the receptive fields of cortically activated cells recorded in the superficial laminae of the colliculus. However, there was considerably less retinotopic fidelity for the cortical areas from which cells isolated in the deeper laminae could be driven. This suggests a greater degree of convergence from relatively widespread cortical regions upon visual cells of the deeper laminae. The visual response properties (directional selectivity, speed preferences, and receptive field organization) of the cortically activated cells did not differ appreciably from the overall sample of visual cells recorded in the colliculus. Only 3 of the 159 cells tested were driven by stimulation of the contralateral visual cortex and two of these were responsive only at very long latencies.
A comparative study of the neurons of origin of the spinocerebellar afferents in the rat, Cat and squirrel monkey based on the retrograde transport of horseradish peroxidase
Authors: Snyder Russell L. , Faull Richard L. M. , Mehler William R. 
Published: January 2005

AbstractThe cell bodies of the neurons of the spinocerebellar pathways were examined using large injections of horseradish peroxidose into the cerebellum. Sections of each spinal segment were examined with both the DAB and the de Olmos O‐dianisidine techniques. Results common to all three species were found. In Clarke's nucleus, the central cervical nucleus, and the spinal border cells there were many heavily labeled cells. Clarke's nucleus was found to project primarily ipsilaterally; the spinal border cells primarily contralaterally; and the central cervical nucleus bilaterally. In addition to these aggregates of spinocerebellar neurons there were numerous labeled neurons scattered throughout the spinal grey. Labeled neurons were found in all portions of the spinal grey except the substantia gelatinosa and lateral cervical nucleus and occurred in all spinal segments. They varied in morphology from large multipolar neurons, found predominantly in the ventral horn to small globular and fusiform neurons that were most abundant in the dorsal horn. These cells were found to project both ipsilaterally and contralaterally. Results common to only two of the species examined were also found. In the squirrel monkey and the cat, but not the rat, the marginal layer of the dorsal horn in all segments of the spinal contained numerous labeled neurons. These marginal neurons were especially numerous in the squirrel monkey, where as many as 13 to 16 labeled neurons per section of the dorsal horn were found. In the rat and the squirrel monkey but not the cat, some intensely labeled large multipolar neurons were found in the sacral and caudal segments. These are the cells of Stilling's nucleus, a column of cells similar in position and orientation to that of Clarke's column but different in its projections and details of cytoarchitecture. Thus we have not only confirmed that Clarke's nucleus, the central cervical nucleus, and the spinal border cells project to the cerebellum but we have also found several new sources of spinocerebellar afferents.
Cell bodies of origin of reticular projections from the superior colliculus in the cat: An experimental study with the use of horseradish peroxidase as a tracer
Authors: Kawamura Koki , Hashikawa Tsutomu 
Published: January 2005

AbstractBy use of the retrograde axonal transport of horseradish peroxidase (HRP), the projection from the superior colliculus (SC) to the brain stem reticular formation (RF) was investigated in the cat. A 0.2–0.5 μl of a 50% suspension of Sigma VI HRP was injected stereotactically in various portions of the pontomedullary RF, and, as a control to the injection to the RF, in the inferior olive or in the spinal cord.Labeled cells were found within and deep to the intermediate gray layer of the SC in the cats which survived for two or three days after HRP injection. The number of the labeled cells varied, according to the difference in the site of injection and the amount of injected HRP. About 400 labeled cells in twenty 50‐μm sections, taken every fifth of the SC, occurred throughout its rostrocaudal extent, particularly in the case where the medial portion of the border zone of the nucleus reticularis pontis oralis and the caudalis (R.p.o.‐R.p.c. zone) or the border zone of the nucleus reticularis pontis caudalis and the gigantocellularis (R.p.c.‐R.gc. zone) was heavily stained after three days of survival period. From 10 to 15% of these labeled cells were large in size (more than 40 μm in diameter), 20–30% were medium sized and the rest (60–70%) were small (10–25 μm). On the other hand, when HRP was placed in the inferior olive only eight cells were labeled in the SC, seven of which were small and medium sized. When HRP was injected in the gray matter of C1C3 level of the spinal cord, a total of 70 tectal cells (14, 42, and 14 were large, medium, and small cells, respectively) were observed to be labeled.The findings of the tectoreticular neurons are discussed and compared with those of the tectoolivary and the tectospinal neurons. Thus the three kinds of tectal neurons are located within and deep to the intermediate gray layer. The number of the labeled cells and the percentage of the collicular neurons of different sizes are obviously different among the three different projections.Topographic correlations between the SC and the RF could not be discerned in the present materials. These results were discussed in relation to possible influences of the tectoreticular neurons upon the extraocular and the spinal motoneurons.
Development of the dorsal lateral geniculate nucleus in the cat
Authors: Kalil Ronald 
Published: January 2005

AbstractThe development of the lateral geniculate nucleus has been studied systematically in Nissl preparations from a series of cats that ranged in age from newborn to adult. In addition, preliminary observations are reported at two stages of fetal development.It was found that laminae develop in the lateral geniculate nucleus near the time of birth and continue to differentiate during the first postnatal week. During development the major axis of the lateral geniculate rotates approximately 180° in the sagittal plane. The rotation begins prenatally and is not completed until after the twentieth postnatal week.The volume of the lateral geniculate was computed at different ages and it was determined that during the first postnatal month the nucleus attains two‐thirds of its adult size. However, the rate of growth declines markedly thereafter, and final volume, like final position, is not achieved until late in development.The cross‐sectional areas of lateral geniculate neurons were measured at four locations in the nucleus in each animal. The locations represented the following parts of the visual field: the paracentral and inferior peripheral fields in the binocular segment of lamina A; the monocular segment of lamina A; and the paracentral field in lamina A1. Neurons in each of these locations grow at approximately the same rate and are essentially fully grown by 56 days. Cell size histograms show that more large cells are found in lamina A1 and more small cells in the monocular segment than elsewhere in the dorsal laminae. Unlike the retina, there appears not to be a gradient of development in the lateral geniculate nucleus from center to periphery, at least in terms of cell body size at the ages studied. On the contrary, that part of the lateral geniculate nucleus which represents the paracentral visual field is the last segment in the dorsal laminae to achieve a mature cell size distribution.Finally, a discrete class of small spindle‐shaped neurons was observed in the lateral geniculate nucleus ventral and caudal to the C laminae during the first two postnatal weeks. These cells possess a leading and trailing cytoplasmic process and are distinctly different from cells in the main laminae. It is suggested that these spindle‐shaped cells may be neurons that are still in the process of migration or differentiation in the postnatal animal.
An autoradiographic study of the rubroolivary tract in the rhesus monkey
Authors: Strominger Norman L. , Truscott Timothy C. , Miller Richard A. , Royce G. James 
Published: January 2005

AbstractAutoradiographic tracing methods were employed to study the course and distribution of the rubroolivary tract following unilateral injections of tritiated leucine into the rostral red nucleus of seven rhesus monkeys. A topographic organization of projections to the ipsilateral principal nucleus of the inferior olivary complex was demonstrated. Lateral and medial portions of the rostral red nucleus projected to medial parts of the dorsal and ventral laminae of the principal inferior olive respectively; neurons in intermediate lateralities emitted fibers which terminated in lateral parts of the principal olive. Injections involving the oral end of the rostral red nucleus elicited label overlying the medial accessory olive in addition to the principal nucleus. Projections to the medial accessory olive may have arisen from the rostral end of the red nucleus and/or the immediately adjacent tegmentum. There were no projections to the dorsal accessory olive. Fibers of rubral origin also were distributed ipsilaterally to several reticular nuclei including the pedunculopontine, pontis oralis, caudalis, and gigantocellularis.