bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of the crayfish stretch receptor in relation to its function
Authors: Tao‐Cheng Jung‐Hwa , Hirosawa Kazushige , Nakajima Yasuko 
Published: January 2005

AbstractThe crayfish slow‐adapting abdominal stretch receptor was fixed under the relaxed or stretched condition. During this procedure action potentials of the sensory neuron were recorded by a suction electrode. The receptor organ consists of a receptor muscle and a sensory neuron with its dendrites embedded in the connective tissue zone in the receptor muscle. From the cell body of the neuron, several “primary dendrites” arise, branch successively into “dendritic branches”, and finally terminate as “dendritic tips”, which are cylindrical processes of fairly uniform diameter. In contrast to the primary dendrites and the dendritic branches, the dendritic tips have neither mitochondria nor sheaths and are embedded in the connective tissue zone or apposed to the receptor muscle with a gap of about 15 nm. Microtubules and smooth ER are seen in all parts of the dendrites. When the receptor is stretched and then fixed with 1.6% glutaraldehyde in 0.12 M phosphate buffer (total osmolarity of this solution is isosmotic with the physiological solution), dendritic tips became more parallel to the long axis of the receptor muscle and showed marked deformation consisting of alternate regions of swelling and shrinkage, resulting in a bead‐like appearance. When fixed with 1.6% glutaraldehyde in 0.2 M phosphate buffer (total osmolarity of this solution is hyperosmotic), the dendritic tips showed less tendency toward such deformation. These results suggest that the dendritic tip membrane is susceptible to stretch and might be the region where the generator potential is produced.
Development of the pyramidal tract in the hamster. I. A light microscopic study
Authors: Reh Thomas , Kalil Katherine 
Published: January 2005

AbstractThe development of the pyramidal tract and other projections from the sensorimotor cortex was studied in the postnatal hamster with both (3H) proline and horseradish peroxidase (HRP) as anterograde tracers. In the 1‐day‐old animal labeled axons extend as far as the pons. Other corticofugal fibers have penetrated into the corpus striatum and the thalamus. By 2 days postnatally, the pyramidal tract has grown to midmedullary levels and there is substantial retrograde (HRP) and anterograde labeling in the thalamus. The pyramidal decussation is formed at 3 days of age and by 4 days the pyramidal tract has descended in the dorsal funiculus as far as midcervical spinal cord. Corticofugal fibers invade the pontine nuclei at 4 days and both the dorsal column nuclei and the superior colliculus at 6 days of age. At 6 days the pyramidal tract can be traced to midthoracic levels of the spinal cord, by 8 days the tract reaches lumbar levels, and by 14 days it has completed its caudal growth to the coccygeal spinal cord. Fibers first penetrate the gray matter of a given spinal cord level approximately 2 days after the tract has grown past that level in the dorsal funiculus. Pyramidal fibers continue their lateral growth into the dorsal horn at all levels of the cord throughout the third postnatal week such that by 21 days of age the pyramidal tract appears similar to that of the adult.The projections from sensorimotor cortex to the pontine nuclei, the superior colliculus, and the dorsal column nuclei appear to have a pattern similar to that of the adult soon after the fibers grow into these structures. There is a consistent delay of 2 to 3 days between the arrival of the pyramidal tract axons in the white matter adjacent to target structures and their innervation of a given terminal field. The pyramidal tract grows more quickly through the dorsal funiculus of the spinal cord than it does along the ventral surface of the medulla. Extensive elongation of pyramidal tract axons is achieved long before the growth and differentiation of the sensorimotor cortical neurons from which they originate. Finally, the pyramidal tract appears to grow as a compact bundle and not by the addition of temporally staggered groups of fibers. The relatively protracted period of innervation of the spinal cord by the pyramidal tract coupled with the immaturity of the cortical neurons at birth may be factors contributing to the significant regrowth of pyramidal tract axons severed early in development.
Identified neurons in an insect embryo: The pattern of neurons innervating the metathoracic leg of the locust
Authors: Whitington Paul M. , Seifert Eveline 
Published: January 2005

AbstractThe population of motorneurons which send axons to the metathoracic leg of the locust embryo has been stained by a cobalt backfilling technique. Embryogenesis lasts 11 days and an adultlike distribution of motorneuron cell bodies is seen as early as day 6: Several identified adult motorneurons can be recognized in the embryo. The total number of filled cells, the overall distribution of stained cell bodies, and the relative positions of identified neuron cell bodies do not change between 6 days and hatching. No motorneurons are stained which are clearly not leg motorneurons, and an adult pattern ofaxon branching at the level of peripheral nerve roots is already present at day 6. These observations provide information about the timing of motorneuron production and motor axon growth into the embryonic limb. The development of central dendritic arborizations can also be followed. The results are discussed with respect to mechanisms for neuron determination and differentiation.
Projections from the superior colliculus and the neocortex to the pulvinar nucleus in Galago
Authors: Raczkowski Denis , Diamond I. T. 
Published: January 2005

AbstractWe have studied the projections from the superior colliculus and the neocortex to the pulvinar nucleus in Galago senegalensis. by using the retrograde transport of horseradish peroxidase (HRP). Injections of various parts of the pulvinar complex, both the inferior and superior divisions, both the tectorecipient zone and the nontectorecipient zone as defined by Glendenning et. al. ('75), produce labeled cells in the lower tier of stratum griseum superficiale. The distribution of labeled cells in the superior colliculus varies with the locus of the injection, indicating a retinotopic projection system from the entire superior colliculus to all sectors of the pulvinar complex.These experiments also provide an opportunity to study the distribution and laminar origin ofneurons giving rise to cortical descending projections. The entire visual cortex projects onto the pulvinar complex. The cells of origin can be divided into two populations–one located in layer V and the other in layer VI. In seven of the nine cases reported, the layer V population is restricted entirely or mainly to the striate area. In the two exceptional cases, the layer V population is located in the adjacent extrastriate cortex, areas 18 and 19. The difference in the layer of origin of the cortical descending fibers reflects a difference in the layer of termination of the reciprocal ascending projection.These findings identify the entire visual field as primary visual cortex. The importance of this conclusion is underscored by the fact that the visual field comprises as much as one‐half of the whole neocortex.
(3H)‐Dihydrotestosterone in catecholamine neurons of rat brain stem: Combined localization by autoradiography and formaldehyde‐induced fluorescence
Authors: Heritage Aileen S. , Stumpf Walter E. , Sar Madhabananda , Grant Lester D. 
Published: January 2005

AbstractA combined formaldehyde‐induced fluorescence (FIF)‐autoradiography procedure was used to determine how and where the androgen, dihydrotestosterone (DHT), is associated with catecholamine systems in the rat brain. With this dual localization method, (3H)‐DHT target sites can be visualized in relation to catecholamine perikarya and terminals. In the hindbrain, catecholamine neurons adjacent to the fourth ventricle (group A4), the nucleus (n.) olivaris superior (group A5), the n. parabrachialis medialis (group A7), and in the locus coeruleus (group A6) and subcoeruleal regions, as well as in the substantia grisea centralis, concentrate (3H)‐DHT in their nuclei. (3H)‐DHT target neurons appear to be innervated by numerous catecholamine terminals in the following hindbrain regions: n. motorius dorsalis nervi vagi, n. tractus solitarii, n. commissuralis, n. raphe pallidus, n. olivaris inferior, the ventrolateral portion of the substantia grisea centralis, n. cuneiformis, and the ventrolateral reticular formation in the caudal mesencephalon. In the forebrain, (3H)‐DHT concentrates in nuclei of catecholamine neurons located in the n. arcuatus and n. periventricularis (group A12). In addition, (3H)‐DHT target neurons appear to be innervated by numerous catecholamine terminals in the following forebrain regions: n. periventricularis rotundocellularis, n. paraventricularis, n. dorsomedialis, n. periventricularis, area retrochiasmatica, n. interstititalis striae terminalis (ventral portion), and n. amygdaloideus centralis.The disclosure of a morphologic association between (3H)‐DHT target sites and certain brain catecholamine systems suggests a close functional interdependence between androgens and catecholamines.
Development of axosomatic synapses of the Xenopus spinal cord with special reference to subsurface cisterns and C‐type synapses
Authors: Watanabe Hiroshi 
Published: January 2005

AbstractThe relationships of highly flattened subsurface cisterns (SCCs) were investigated electron microscopically in the spinal cord at various devel‐ opmental stages of tadpoles and adult toads, Xenopus laeuis.In medial ventral motor cells (MVCs) of the adult, more than 90% of 156 SSCs examined were situated postsynaptically. Similarly, more than 909% of 540 SSCs in lateral motor column cells (LMCs) were postsynaptic. By contrast, in early developmental stages, the SSCs were initially formed by regional flattening of cisterns of rough‐surfaced endoplasmic reticulum just beneath the cell surfaces opposite to glial processes. Then, the glial processes were displaced by nerve endings with an elongated bouton, and thus the C‐type synapses were formed. The ratio of post‐ synaptic SSCs to the total SSCs reached the adult level at around Stage 60. This finding suggests that the SSCs in the MVCs and LMCs draw a certain type of nerve ending to form C‐type synapses. Such a mechanism is totally lacking in the dorsal and lateral small nerve cells, since the SSCs in these cells were always situated under the surface opposite to glial processes throughout the developmental stages and in the adult.In mature C‐type synapses, an aggregate of synaptic vesicles and a structural specialization of presynaptic membrane occurred only at the region where the postsynaptic membrane was associated with the SSC. The postsynaptic membrane itself of the C‐type synapse showed no marked structural specialization at any stage of development or in the adult.The postsynaptic SSC in the mature C‐type synapse seems to be involved in some way in the reception of synaptic transmission.
Connections of the amygdala of the rat. IV: Corticoamygdaloid and intraamygdaloid connections as studied with axonal transport of horseradish peroxidase
Authors: Ottersen Ole P. 
Published: January 2005

AbstractThe corticoamygdaloid and intraamygdaloid projections of the rat were studied by the use of retrograde transport of horseradish peroxidase (HRP). Observations based on anterograde transport of the enzyme were exploited to determine the course of the intrinsic connections. The HRP was injected stereotactically by means of iontophoresis. Most of the amygdaloid nuclei were selectively injected, and all but a few were reached by more than one approach.The vast majority of corticoamygdaloid fibers was found to originate in cortical areas defined as allocortical (Stephan, 1975). From the medial frontal cortex the central amygdaloid nucleus (AC) receives a hitherto undescribed projection originating in the tenia tecta; and both the AC and the lateral amygdaloid nucleus (AL) receive fibers from the prelimbic and infralimbic areas. The anterior cingulate area entertains a weak connection with the basolateral amygdaloid nucleus (BL). As to the insular cortex, the posterior agranular insular area projects to all amygdaloid subdivisions; the BL, AC, and the anterior cortical nucleus (COa) receive, in addition, fibers from the ventral agranular area. The prepyriform cortex connects with the entire amygdala except the medial nucleus (Am)The amygdala receives afferents from a transitional area between the amygdala and the entorhinal area. The entorhinal area proper is related to the amygdala via projections from the ventral part of the lateral entorhinal area to the AL and from the dorsal part of the lateral entorhinal area to the BL. The former nucleus also receives fibers from the perirhinal region. Additional amygdalopetal connections from the hippocampal region include a previously undescribed projection from the temporal two‐thirds of CA1 to the AL and BL and to the posterior cortical nucleus (COp) with the adjacent periamygdaloid cortex (PAC). The subiculum projects to the AL, and more modestly to other amygdaloid nucleiThere is an extensive network of intraamygdaloid connections, the Am and AC being the only nuclei not giving rise to intrinsic fibers.
Physiological and morphological identification of two types of on‐center bipolar cells in the carp retina
Authors: Saito Takehiko , Kujiraoka Toru 
Published: January 2005

AbstractTwo types of on‐center bipolar cells, rod‐ and cone‐dominant bipolars have been identified in the dark‐adapted retina of the carp by means of intracellular recordings and Lucifer‐yellow dye injection. They differ physiologically and morphologically in the following respects: (1) responses of rod‐dominant cells to bright lights are characterized by a tansient depolarization followed by a smaller sustained depolarization, while those of cone‐dominant cells are approximately rectangular; (2) the cone‐dominant cells are about 1.5 log units less sensitive to light than the rod‐dominant cells; (3) the latency of the response is shorter in the cone‐dominant cells than in the rod‐dominant cells; (4) the mean diameters of the cone‐dominant cell receptive field (0.7 mm) and dendritic field (90 μm) are larger than those of the rod‐dominant cell receptive field (0.5 mm) and dendritic field (56 μm); (5) the mean diameter of the cone‐dominant cell soma (8 μm) is smaller than that of the rod‐dominant cell soma (13 μm); and (6) the terminations of the cone‐dominant cell axons form a ramification (67 μm mean diameter) in contrast to a big terminal swelling of the rod‐dominant cell axons (37 μm mean diameter). At least two ionic mechanisms are responsible for generating the depolarizing response of on‐center bipolar cells, one having a reversal at a positive potential and the other at a negative potential. Responses with a negative reversal potential only are obtained from some of cone‐dominant cells and responses with a positive reversal potential only are obtained from some other cone‐dominant cells and the rod‐dominant cells. There are a large number of bipolar cells that respond by both ionic mechanisms, although the ratio between them varied considerably in different cells.
Transplantation of reaggregates of embryonic neural retinae to neonatal rat brain: Differentiation and formation of connections
Authors: McLoon Linda Kirschen , Lund Raymond D. , McLoon Steven C. 
Published: January 2005

AbstractEmbryonic day 14 neural retinae were dissociated into single cells and reaggregated prior to transplantation over the superior colliculi of newborn rats. One month after transplantation, the brains of the host rats were examined for transplant differentiation and the formation of projections from the transplant to the host brain.All reaggregated retinal transplants differentiated in the host brain, showing normal lamination and cellular morphology. Electron microscopic examination demonstrated normal synaptology within the transplanted retinal neuropil. Horseradish peroxidase injections into the host superior colliculus retrogradely filled cells within the transplant. These cells were found in the lamina corresponding to the ganglion cell layer and displayed a morphology characteristic of normal ganglion cells. Lesions of the transplants confirmed the projection of the reaggregated retinal transplants to superior colliculus. Degeneration was also traced into a number of other nuclei that are normally retinorecipient. The presence of degenerating synaptic terminals resembling those seen after eye removal in control rats was confirmed by electron microscopic examination.It appears that despite disruption of initial cell‐cell associations early in retinal development and prior to transplantation, the reaggregated transplants retain the ability to differentiate and form appropriate connections with the host brain.
Ontogeny of the leucine‐enkephalin neuron system of the rat: Immunohistochemical analysis. I. Lower brainstem
Authors: Senba Emiko , Shiosaka Sadao , Hara Yoshinobu , Inagaki Shinobu , Kawai Yuriko , Takatsuki Kenichi , Sakanaka Masahiro , Iida Hisashi , Takagi Hiroshi , Minagawa Hideo , Tohyama Masaya 
Published: January 2005

AbstractOntogeny of the leucine‐enkephalin (L‐Enk) neuron system in the lower brainstem of the rat was investigated by means of indirect immunofluorescence.L‐Enk‐containing cells first appear in the primordium of the medullary reticular formation just medial to the n. tractus spinalis nervi trigemini at the level of the rostral half of the inferior olivary nucleus, in the n. cuneiformis, and in the mesencephalic reticular formation of the fetus at gestational day 16 (14–15‐mm embryos). From that time onward, L‐Enk‐containing cells appear in various areas of the lower brainstem one after another until birth. After birth, although L‐Enk‐containing cells decrease slightly in number as the rats grow, L‐Enk‐containing fibers continue to increase in number.
The morphology and connections of the posterior hypothalamus in the cynomolgus monkey (Macaca fascicularis). I. Cytoarchitectonic organization
Authors: Veazey R. B. , Amaral D. G. , Cowan W. M. 
Published: January 2005

AbstractThe cytoarchitectonic organization of the posterior hypothalamus of the cynomolgus monkey (Macaca fascicularis) was analyzed in Nissl, Golgi, acetylcholinesterase, and reduced silver preparations. The region consists of a number of cell masses that differ considerably in their discreteness and in the homogeneity of their neuronal populations. The nuclei identified include: the medial mamillary nucleus (in which at least three distinct subdivisions can be recognized—a pars medialis, a pars lateralis, and a pars basalis); the small‐celled nucleus intercalatus; the large‐celled lateral mamillary nucleus; a single premamillary nucleus; the tuberomamillary nucleus; the posterior hypothalamic nucleus; the caudal extension of the lateral hypothalamic area; the supramamillary area; and the paramamillary nucleus (which appears to correspond to the nucleus of the nucleus of the ansa lenticularis of other workers). As a basis for the subsequent experimental study of the efferent connections of the posterior hypothalamus, the location of each of these cell masses is described and illustrated in a series of low‐power photomicrographs, as are the form and distribution of the resident neuronal populations of the various components of themamillary complex as seen in Golgi preparations.
The serotonin neurons in nucleus raphe dorsalis of adult rat: A light and electron microscope radioautographic study
Authors: Descarries Laurent , Watkins Kenneth C. , Garcia Sylvia , Beaudet Alain 
Published: January 2005

AbstractThe serotoninergic nerve cell body population of nucleus raphe dorsalis (RD) was identified by radioautography following cerebroventricular instillation of tritiated serotonin ([3H]5‐HT) in adult rats pretreated with a monoamine oxidase inhibitor. Series of histological sections taken throughout the midbrain and upper pons exhibited a similar distribution and number of labeled nerve cell bodies in RD after prolonged administration ofeither 10−5 or 10−4 M [3H]5‐HT or 10−4 M [3H]5‐HT and 10−3 M nonradioactive noradrenaline. This allowed systematic mapping and quantification of serotoninergic nerve cell bodies at various levels of the RD. Their extrapolated total number averaged 11,500. Twice as many unreactive (nonserotoninergic) neurons were present within the same region. In electron microscope radioautographs, the labeled cells were usually larger (17.9 μm mean diameter) than their unlabeled congeners (13.1 μm), but stereological sampling of their perikarial organelle content failed to reveal any difference in cytoplasmic composition. Few [3H]5‐HT‐labeled axonal varicosities were observed in RD and none were found in close apposition or in synaptic junction with labeled nerve cell bodies, dendrites, or unreactive perikarya. A detailed statistical analysis of silver grain distribution in both labeled and “unlabeled” nerve cell bodies indicated that in the former, but not in the latter, dense bodies had a relatively high affinity for [3H]5‐HT. Mitochondria and the cytoplasmic membrane were the only other organelles to show higher labeling indices in labeled than in unlabeled cells. Other sites of[3H]5‐HT localization could be ascribed to artefactitious cross‐linkage of the tracer by the fixative, since they had the same relative affinity in the two cell populations. These results provide new insights into the morphology and cytofunctional properties of the 5‐HT neurons of rat RD.
Mature Purkinje cells in cerebellar tissue cultures: An ultrastructural study
Authors: Blank Nathan K. , Seil Fredrick J. 
Published: January 2005

AbstractMature Purkinje cells in mouse cerebellar tissue cultures were morphologically analyzed by electron microscopy. Explants maintained for 19 to 31 days in vitro contained Purkinje cells that were similar in most respects to those described in vivo except for incomplete arborization of the dendritic trees. Typical features included (1) absence of Purkinje cell perisomatic spines; (2) a paucity of naked Purkinje cell dendritic spines; (3) a 1:1 relationship of Purkinje cell dendritic spines to parallel fiber terminals; and (4) almost complete astroglial investment of Purkinje cell somata and dendrites. Minimal extracellular space was present in the neuropil of the explants and unusual synapses involving Purkinje cells were absent. Atypical features described by some investigators may be a function of retarded development in suboptimal culture conditions and do not represent the limit of tissue culture methodology.