bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neuronal morphology of the rabbit cochlear nucleus
Authors: Disterhoft John F. , Perkins Randolph E. , Evans Scott 
Published: January 2005

AbstractThe cytoarchitecture of the cochlear nucleus in young adult albino rabbits (Cuniculus oryctologus) has been examined in Nissl‐ and Golgi‐impregnated material to compare rabbit cochlear nucleus with other mammalian species. Cochlear nucleus was subdivided into anteroventral (AVCN), posteroventral (PVCN), and dorsal (DCN) regions, as in other mammals. AVCN was characterized by bushy cells and stellate cells. The “bushy” dendritic trees of adjacent bushy cells often overlapped. PVCN was characterized by octopus, elongate, and stellate cells. The dendritic trees of adjacent octopus cells extended in a parallel array across the auditory nerve fibers. DCN had molecular, fusiform and polymorphic layers. The fusiform cell layer was especially prominent, with the fusiform cells appearing visually to be the organizing elements in DCN. The large cells in DCN were the fusiform and giant neurons; the medium cells were the stellate and elongate neurons; the small cells were the cartwheel, small stellate, and granule cells. The cochlear nucleus of rabbit is essentially similar in cytoarchitectural organization to other mammalian species which have been studied. The detailed morphology of the various cell types seen in Golgi preparations is quite similar to that of cat (Brawer et al., '74), although some differences do exist.
Location of motoneurons supplying individual muscles in normal and grafted supernumerary limbs of Xenopus laevis
Authors: Rubin David I. , Mendell Lorne M. 
Published: January 2005

AbstractThe purpose of this study was to investigate innervation of transplanted supernumerary hindlimbs in the frog (Xenopus laevis). Motoneurons innervating identified muscles in normal and supernumerary limbs were located by the method of retrograde transport of HRP after intramuscular injection. In the lumbar spinal cord of normal Xenopus, motoneurons supplying medial hindlimb muscles, which are derived from the ventral muscle mass during development, are located at the medial end of the motor column; those innervating lateral, dorsallyderived muscles, lie at the lateral end of the motor column. In animals with supernumerary limbs, motoneurons supplying the transplant usually occupied the same mediolateral position as those supplying the same muscle in the normal limb. However, the rostrocaudal location of these motor pools exhibited greater flexibility. When the transplant was innervated by a rostral nerve of the lumbar plexus, motoneurons supplying gastrocnemius could be located in a region of the spinal cord whose motoneurons do not normally innervate this muscle. There is thus no rigid requirement that gastrocnemius motoneurons be located at specific segmental levels. Motoneurons supplying gastrocnemius in the normal limb on the experimental side showed normal rostrocaudal distributions, indicating little rearrangement of these motor pools. Dorsal root ganglion cells labeled after HRP injection could be concentrated in a ganglion which normally supplies little or no innervation to the injected muscle. The location of these cells confirmed the segmental source of sensory innervation of the extra limb; i.e., there was no stray innervation. Animals with supernumerary limbs exhibited little or no increase in the number of motoneurons on the extra limb side. In contrast, dorsal root ganglion cell populations exhibited a large increase on the experimental side.
Ultrastructure of the pyramidal basket cells in the dentate gyrus of the rat
Authors: Ribak Charles E. , Anderson Lynn 
Published: January 2005

AbstractLight and electron microscopic preparations were used to examine the somata and dendrites of the large pyramidal basket cells in the dentate gyrus. Results from previous Golgi studies have shown that the somata of these neurons are located beneath the granule cell layer and that their axons are distributed around the granule cell somata, where they form basket endings. The results of the present study indicate that the morphology of the pyramidal basket cell differs in many ways from that of the granule cell, aside from the obvious difference of their greater size. The pyramidal basket cells display infolded nuclei and intranuclear rods and sheets, and these characteristics are not found in granule cells. The pyramidal basket cells also show a greater abundance of cisternae of granular endoplasmic reticulum and other perikaryal organelles. Furthermore, the somata and the smooth dendrites of these neurons form both symmetric and asymmetric synaptic junctions. The results of this study indicate that the pyramidal basket cells have distinct ultrastructural characteristics that are shared by other GABAergic neurons in the cerebral cortex. It is suggested that some of these characteristics may underlie the role played by these cells in providing GABA‐mediated, tonic inhibition of other neurons.
Cortical connections of the pulvinar nucleus in Galago
Authors: Raczkowski Denis , Diamond I. T. 
Published: January 2005

AbstractIn the first series of experiments, small amounts of HRP were injected into areas 17, 18, and 19 and each of the cytoarchitectonic areas of the temporal lobe. The resulting distributions of labeled cells fell into a number of distinctive classes. For example, after injecting the temporal anterior area (Ta), the labeled cells occupied a band on the ventral border of the inferior division of the pulvinar complex; after injecting the temporal ventral area (Tv), the labeled cells were concentrated in the medial extremity of the superior division. In spite of the distinctiveness of these different distributions, there was evidence that in areas that we know to contain a representation of the visual field, the injection of the same part of the field led to labeled cells in the same part of the pulvinar nucleus. Thus, when the representation of the center of the field was injected in areas 17 or 18 or Tm (the temporal middle area), labeled cells were found in the dorsal part of the rostral half of the inferior division. The distinctiveness of the different distributions did not obscure certain features common to all experiments: labeled cells were always found in both subdivisions of the pulvinar complex, and there was always continuity between the population of labeled cells in the inferior division and the population of cells in the superior division.Wherever the site of the injection in the extrastriate region, some labeled cells were found in the caudal half of the inferior division. Since the caudal half of the inferior division corresponds approximately to the tecto‐recipient zone as defined earlier, the entire temporal lobe, except for the auditory areas, is visual cortex. Evidence was also found for an overlap in the striate cortex between the projections of the lateral geniculate body and the pulvinar nucleus. In conclusion, the pulvinar complex projects to a vast area of cortex, including all of the occipital lobe and most of the lateral surface of the temporal lobe. This entire region, which comprises a good part of the whole of the neocortex, can be regarded as visual cortex.A second series of experiments involved cortical injections of tritiated amino acids. The results showed that the projections from the thalamus to cortex were precisely reciprocated by descending projections from cortex to thalamus. The results also served as a way of confirming the results of the first set of experiments.
The pretectal region of the cat: A structural and topographical study with stereotaxic coordinates
Authors: Avendaño C. , Juretschke M. A. 
Published: January 2005

AbstractUsing Nissl and myelin staining methods, the structure of the pretectal region has been analyzed in the cat. From this study and a review of the literature, three groups of cell populations have been identified, each made up of several parts or nuclei: 1) Nuclei of the posterior commissure, including dorsal, lateral, and ventral divisions; 2) A dorsolateral group of nuclei, which includes the pars lateralis and pars medialis of the nucleus of the optic tract, and the nucleus olivaris; 3) An intermediate nuclear group (pretectal nuclei, “sensu stricto”) composed of the nuclei posterior, subopticus, anterior (with two portions, compacta and reticularis), and medialis.Stereotaxic coordinates of this region were also determined and plotted both on coronal and horizontal sections. The combined use of several spatial planes has proven to be of great value in studying transitional regions such as the pretectal region.
Presence of the ruffed cell in the olfactory bulb of the catfish, Parasilurus asotus, and the sea eel, Conger myriaster
Authors: Kosaka Toshio , Hama Kiyoshi 
Published: January 2005

AbstractThe ruffed cell is present in the olfactory bulb of the catfish, Parasilurus asotus, and of the sea eel, Conger myriaster. Its morphological features have been studied by light microscopy, high‐voltage electron microscopy, and conventional electron microscopy.The ruffed cell of the catfish is very similar to that of the goldfish in its location and in its structural features. It has a spheroidal or ovoid cell body about 15 to 30 μm in diameter. Several dendrites arise from the cell body to form a rounded dendritic field about 100 μm in diameter near the cell body. The initial unmyelinated portion of its axon (IP) consists of a shaft and many protrusions arising from it. The shaft, about 1 μm in diameter, extends for about 100 to 200 μm, where it acquires a myelin sheath. The protrusions intermingle with one another in a complex manner to form a rather discrete spheroidal field about 20 to 50 μm in diameter, located in the vicinity of the cell body.In contrast, the ruffed cell of the sea eel differs rather significantly from that of the goldfish in its morphological features. The ruffed cell of the sea eel is of a bipolar type. One thick dendrite arises from the cell body and extends for about 50 to 100 μm, where it gives rise to many thread‐like dendritic branches. The IP arises from the cell body as a smooth thin process. However, about 30 to 70 μm distant from its origin, many elaborate protrusions arise from the axonal shaft. These intermingle with one another to form a spheroidal or ovoid field about 20 to 40 μm in diameter. Distal to this protrusion‐bearing part, the axon continues as a smooth, thin process.In spite of these differences in structural features, the ruffed cell of the catfish and that of the sea eel are very similar in their synaptic features in the nest (the special synaptic field around the ruffed cell IP, composed of its protrusions, of granule cell dendrites, and of other neuronal processes); that is, synapses between the ruffed cell IP (its shaft and protrusions) and granule cell dendrites and serial synapses made by the ruffed cell IP, granule cell dendrites, and perinest cell dendrites.These results suggest that the ruffed cell is generally present in the teleostean olfactory bulb, although its detailed structural features may vary from species to species. Moreover, the neuronal organization of the olfactory bulb seems to be fundamentally similar in various species of teleosts.
The sensitive period in the development of the trigeminal system of the neonatal rat
Authors: Belford Gary R. , Killackey Herbert P. 
Published: January 2005

AbstractIn previous studies we have described vibrissae‐related segmentation in the brainstem, thalamus, and cortex of the neonatal rat. Using succinic dehydrogenase (SDH) histochemistry, we delineated the time course in development of the normal segmentation at each level of the trigeminal system and the aberrant segmentation resulting from follicle damage at birth (Killackey and Belford, '79; Belford and Killackey, '79a, b). The present study examines the aberrant patterns that result from damage to the vibrissae follicles at different ages, comparing the patterns at the different levels of the trigeminal system.The present study indicates a number of similarities between the central representations of the vibrissae. First, the patterns are similar within each of the three representations in the trigeminal nuclei for removal at a given age in a particular animal. These changes include a decrease in SDH density but a maintenance of normal row widths. Second, the patterns are similar within both the ventrobasal complex and layer IV of somatosensory cortex for removal at a given age in a particular animal. These changes include a fusion of individual clusters into bands, and a decrease in band width, but maintenance of normal SDH density. Third, the effects of damage to a row of vibrissae follicles at different ages are graded. Earlier damage produces more marked aberrations. Fourth, for all of the structures, the transition between bands and clusters occurs with damage at the same age. Further, the last age at which damage produces aberrant patterns is Day 3 for all of the structures. Thus, the data suggest that there is one sensitive period for pattern alteration in the entire central trigeminal system.
The organization of the lateral posterior nucleus in neonatal golden hamsters
Authors: Crain Barbara J. , Hall William C. 
Published: January 2005

AbstractThe present series of experiments was designed to study how synaptic relationships in the lateral posterior nucleus are altered after neonatal superior colliculus lesions. In this paper, we studied the lateral posterior nucleus with light and electron microscopic techniques at two critical stages: at the time of the initial neonatal tectal lesion and at the onset of the consequent proliferation of retinal axons.At birth, the lateral posterior nucleus is very immature. Very few synapses are present and no degenerating terminals were found 6 hours after a tectal lesion. Thus, very few, if any, tectal axons have established connections in the nucleus by this time and the optic tract terminals which proliferate as a result of a neonatal tectal lesion are not simply taking over vacated postsynaptic sites.Optic tract terminal proliferation begins 4 to 6 days after removal of the superior colliculus and parallels the development of the normal retinal projections to the superior colliculus and to the dorsal and ventral lateral geniculate bodies (So et al., '78). Thus, the proliferation appears to be an example of increased synapse formation during normal development rather than a case of true “axonal sprouting”.At 6 to 7 days of age, when optic tract terminal proliferation is beginning, the neuropil is still very immature. The terminal types found in the adult nucleus cannot be identified and synaptic clusters have not yet formed. Thus, following neonatal tectal lesions, the lateral posterior nucleus must undergo most of its development not only in the absence of one of its normal projections, but also in the presence of at least one anomalous projection.
Innervation of the urinary bladder in higher primates
Authors: Rockswold Gaylan L. , Bradley William E. , Chou Shelley N. 
Published: January 2005

AbstractStimulating electrodes were placed on the terminal branches of the pelvic nerves to the urinary bladder and the pudendal nerve to the sphincters in seven Rhesus monkeys and two chimpanzees. The proximity of the electrodes to these structures assured organ specificity. Evoked responses produced by stimulation of these terminal nerve branches were recorded in the fascicles and rootlets of the lower thoracic, lumbar, and sacral nerve roots. During identifical stimulating and recording conditions, the amplitude as well as presence or absence of the evoked responses recorded was variable within the various roots. The amplitude of the evoked responses or their absence depended on the number of fibers within a particular fascicle which conducted impulses to the urinary bladder or the urethral and anal sphincters. By this method, it was determined that there was segregation or compartmentalization of the nervous innervation to the urinary bladder and sphincters within the spinal roots.In addition, the segmental spinal cord origin of the innervation of the urinary bladder was determined for the Rhesus monkey and chimpanzee. In the Rhesus monkey, the pelvic nerves to the urinary bladder arose from the first and second sacral segments and to a much lesser extent from the seventh lumbar segment. In the chimpanzee the sacral segments one to four gave rise to innervation of the urinary bladder.
Innervation of the external urethral and external anal sphincters in higher primates
Authors: Rockswold Gaylan L. , Bradley William E. , Chou Shelley N. 
Published: January 2005

AbstractStimulating electrodes were placed on the terminal branches of the pudendal nerve to the external urethral and external anal sphincters. The proximity of the electrodes to the sphincters assured organ specificity. Evoked responses produced by stimulation of these terminal nerve branches were recorded in the fascicles and rootlets of the lower thoracic, lumbar, and sacral nerve roots. By this method, the segmental spinal cord origin of the innervation of the external urethral and anal sphincters was determined for the Rhesus monkey and chimpanzee. The data indicated that the pudendal nerves to the urethral and anal sphincters in the Rhesus monkey arose from the sixth and seventh lumbar spinal segments and the first and second sacral spinal segments which are homologous to the S‐1 and S‐4 segments found to give innervation to these structures in the chimpanzee. The primate experiments thus indicate that the spinal origin of the pudendal nerve was more rostrally located by one segment or more than was the origin of the pelvic nerves to the urinary bladder.
Use of carbon labeling to demonstrate the role of blood monocytes as precursors of the ‘ameboid cells’ present in the corpus callosum of postnatal rats
Authors: Ling E. A. , Penney Don , Leblond C. P. 
Published: January 2005

AbstractCells with features suggestive of ameboid motion and phagocytic properties are observed in the rat corpus callosum during the first few days of life. These cells, herafter referred to as ‘ameboid cells’, have been investigated in several ways.An electron microscopic study of the corpus callosum in 5‐ to 7‐day‐old rats indicated that most ‘ameboid cells’ were typical macrophages, but some displayed features of monocytes, while others appeared to be transitional between the two types. These observations raised the possibility that blood monocytes were the precursors of ‘ameboid cells’.This possibility was tested by injecting a suspension of carbon particles into the circulation of rats of various ages to label and trace monocytes. Within 15 minutes after injection, carbon particles were seen between cells in blood smears as well as in the lumen of capillaries, but not between cells and axons in corpus callosum. By a half hour, a few of the circulating monocytes, and with time, up to half of them, contained carbon particles. Five days after injection, carbon particles were observed in cells of the corpus callosum identified as ‘ameboid cells’ of the monocytic and macrophagic type. Such carbon‐containing cells were seen in many of the animals injected at the age of 0–1 day, in few of those injected at 3–5 days, and in none of the older animals. Since free carbon had not been observed in corpus callosum spaces, it was concluded that ‘ameboid cells’ did not pick up carbon locally. The alternative was that blood monocytes, after ingesting carbon particles in the circulation, migrated to the corpus callosum and settled as ‘ameboid cells’.In the hope of obtaining a direct confirmation of this conclusion, blood cells obtained from carbon‐injected Lewis rats were centrifuged in a Percoll gradient to obtain a fraction which contained 70–80% monocytes, less than 2% granulocytes, and 20–30% lymphocytes. Carbon was present in up to half on the monocytes and 1% of the granulocytes, but not in the lymphocytes; and it was calculated that over 99% of the carbon‐labeled cells were monocytes. The cell fraction was then introduced into the blood circulation of 2‐ to 3‐day‐old syngeneic Lewis rats, and the animals were sacrificed 5 days later. Occasional carbon‐labeled cells appeared not only in liver, spleen and connective tissue, but also in the corpus callosum, where they were identified as ‘ameboid cells’ of the monocytic and macrophagic type. Even though such cells were infrequent, their presence conclusively demonstrated that at least some ‘ameboid cells’ of the corpus callosum were derived from circulating blood monocytes.
Uptake, intra‐axonal transport and fate of horseradish peroxidase in embryonic spinal neurons of the chick
Authors: Chu‐Wang I‐Wu , Oppenheim Ronald W. 
Published: January 2005

AbstractHorseradish peroxidase (HRP) was injected in ovo into the ventral muscle mass of the hind limb of 5‐ to 7‐day‐old chick embryos or into the gastrocnemius muscle of 8‐ to 18‐day embryos and localized histochemically.HRP is extensively incorporated via endocytosis into axonal growth cones or presynaptic terminals in the proximity of the injection site. Much of the tracer is taken up in vesicles and small vacuoles. Most of these are smooth‐surfaced and only a few are bristle‐coated. A small amount of the tracer is also incorporated into the axon terminal through the openings between the axolemma and an intricate membrane channel. The majority of the tracer‐laden vesicles and vacuoles rapidly fuse with one another to become large vacuoles, some of which are transformed into multivesicular bodies (MVBs). In axon shafts, many labeled vacuoles and MVBs are transferred to tubule‐like organelles, which appear to be the primary carrier for transporting the tracer back to the cell bodies in the lumbar spinal cord. HRP arrives in the sensory ganglia about 0.5–1 hour earlier than in the motoneurons of the lateral motor column. The maximal rate of the retrograde axoplasmic transport is about 3.5 mm/hour. After arriving in the cell bodies, HRP is transferred from tubule‐like organelles to discrete vacuoles of various sizes and appearance. Lysosomal dense bodies and HRP‐labeled vacoules can be distinguished ultrastructurally. A fusion of HRP‐labeled vacuoles with lysosomal dense bodies or Golgi vesicles was occasionally observed and the density of HRP‐labeled vacuoles diminished after 2 to 3 days. Most of the HRP‐labeled organelles were found to contain acid phosphatase activity. Therefore, the complete disappearance of HRP by 4 days postinjection is most likely related to lysosomal degradation.Neuronal cell bodies diffusely labeled with HRP were only observed prior to day 6. After day 6, despite various attempts to injure the peripheral axons, only granularly labeled cell bodies were found. This difference may imply that ‘mature’ neurons have a more efficient mechanism for the sequestration of ‘free’ HRP in the cytoplasmic matrix into membrane‐bounded organelles.A mature‐like retrograde transport mechanism appears to exist at the earliest stages of axonal growth in vivo.