bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ventral motor nucleus of the cervical enlargement in some mammals; its specific afferents from the lower cord levels and cytoarchitecture
Authors: Matsushita Matsuo , Ueyama Teizo 
Published: May 2005

AbstractSpecific projections from the lower spinal cord to the ventral motor nucleus of the cervical enlargement were studied in four mammalian species (cat, rabbit, dog and rat) with the Nauta and the Fink‐Heimer methods.Following hemisection of the lower spinal cord a medium amount of degeneration in laminae VII and VIII and scanty degeneration in the dorsolateral part of lamina IX were observed ipsilaterally at the levels from C6 to T2. In contrast, in all of these animals very dense and circumscribed degeneration was seen in a special ventral or ventrolateral cell group of lamina IX, designated here as ventral motor nucleus (VMN). Cytoarchitectonic study shows that this nucleus exists in the ventral or ventrolateral part of lamina IX from the caudal C7 to the rostral T1 segments, attaining the highest development in the C8 segment.Projections of short descending propriospinal fibers and dorsal root fibers to this nucleus were also studied in cats and rabbits. There was a small projection from a neighboring rostral segment, but no termination was found of dorsal root fibers. These results indicate that VMN in the C7 to the T1 segments is a special cell group which receives predominantly a strong projection from the lower cord levels of the same side.
Autoradiographic investigations of glial proliferation in the brain of adult mice. The DNA synthesis phase of neuroglia and endothelial cells
Authors: Korr Hubert , Schultze Brigitte , Maurer Werner 
Published: May 2005

AbstractThe proliferation of glial cells outside the subependymal layer of the lateral ventricle as well as of endothelial cells was studied autoradiographically in the brain of the adult and untreated mouse. The double labeling method with 3H‐ and 14C‐thymidine was applied in order to show experimentally the existence of a DNA synthesis phase (S phase) and to measure its duration. Adult mice received a first injection of 14C‐thymidine, two or four hours later a second injection of 3H‐thymidine and were sacrificed one hour after the last injection by perfusion fixation. Double layer autoradiographs were made from serial sections of the region from the corpus callosum/commissura anterior up to the corpus callosum/commissura fornicis ventralis in order to register purely 3H‐, doubly 3H‐ and 14C‐, and purely 14C‐labeled nuclei. From the ratio of all 3H‐labeled cells with and without 14C to the purely 3H‐labeled cells a DNA synthesis phase of 9.4 ± 0.5 hours for glial cells and one of 11.0 ± 2.2 hours for endothelial cells was obtained. Based on the first appearance of labeled mitoses and labeled pairs of glial cells after injections of labeled thymidine the G2 phase was estimated to be < three hours and G2 + M about five hours. The duration of the measured S phase as well as the appearance of labeled mitoses about three hours after application of labeled thymidine are very similar to these cycle parameters in many other somatic cells in different kinds of animals. This has led to the conclusion that a well‐defined DNA synthesis phase with doubling of the DNA content and a successive mitosis also exists in glial and endothelial cells of the adult mouse brain.
Ascending central gustatory pathways
Authors: Norgren Ralph , Leonard Christiana M. 
Published: May 2005

AbstractThe central gustatory pathways of the albino rat have been traced using a combined electrophysiological‐neuroanatomical technique.Gustatory responses in the medulla were recorded in the region of the solitary nucleus which receives the seventh nerve primary afferents. Fibers traced from lesions of these recording sites did not cross as expected into the medial lemniscus, but instead travelled rostrally to terminate ipsilaterally in a small celled area dorsal and ventral to the brachium conjunctivum as it enters the pons.Since gustatory responses could be recorded in this region it represents a previously undescribed secondary “pontine taste area.” Lesions of PTA result in degeneration of a bilateral ascending pathway travelling in the dorsomedial tegmentum to terminate in the classical gustatory nuclei of the thalamus. Other fibers in this pathway continue rostrally and distribute in the subthalamus, dorsolateral hypothalamus and subpallidal gray in the ventral forebrain.These findings in a mammal resemble those established nearly three quarters of a century ago by Herrick ('05) in the carp, and confirm his prediction that “broad lines of similarity [would be found] between both the peripheral and central gustatory paths in all vertebrates”.
The structure of the optic nerve of the teleost: Eugerres plumieri
Authors: Tapp R. L. 
Published: May 2005

AbstractThe morphology and ultrastructure of the intra‐orbital portion of the optic nerve of Eugerres plumieri is described. Attention is drawn to the ribbon‐like form of the nerve and to the presence of non‐myelinated axons, the majority of which are grouped into a tract at one edge of the ribbon. Fibrous astrocytes and oligodendrocytes are both present and clearly distinguishable. A third type of glial cell which shows evidence of phagocytic activity is also present. It is almost identical in ultrastructure with the multipotential glial cell described by Vaughn and Peters ('68).
Structurally specialized contacts between the photoreceptors of the retina of the axolotl
Authors: Custer Nancy V. 
Published: May 2005

AbstractElectron microscopic examination of the retina of the axolotl, Ambystoma mexicanum, revealed several types of morphological junctions between individual photoreceptors. Distal to the outer limiting membrane of the retina, gap junctions were found between neighboring rods and between neighboring rods and cones. In the external plexiform layer, the synaptic terminals of cones and double cones are often in positions opposite the synaptic ribbons of rod terminals that have been traditionally defined as postsynaptic. A few tight junctions between photoreceptor telodendria were observed. Relationships between the members of double cones are also described.
The central connections of the posterior lateral line nerve of Gnathonemus petersii
Authors: Maler L. , Karten H. J. , Bennett M. V. L. 
Published: May 2005

AbstractThe central distribution of the posterior lateral line nerve (NLLp) was studied in the weakly electric African fish, Gnathonemus petersii. Lesions were made in the ganglion of NLLp and the degeneration traced by means of the Fink‐Heimer technique. NLLp distributes to the ipsilateral posterior lateral line lobe, anterior lateral line lobe, and lobus caudalis cerebelli. The posterior lateral line lobe is laminated and NLLp terminates in an organized manner within three of its six laminae. In addition the projection of NLLp to the posterior lateral line lobe is topographic. The projection of NLLp to the anterior lateral line lobe is more diffusely organized.
Neuromuscular junctions in the leech
Authors: Yaksta‐Sauerland Barbara A. , Coggeshall Richard E. 
Published: May 2005

AbstractNeuromuscular junctions on leech body wall muscle have been described. Based on vesicle morphology, there are two types of junctions, (I) clear vesicle terminals, and (II) dense core vesicle terminals. Further, the dense core terminals are‐of two types, (1) small terminals which appear to directly innervate body wall muscle cells, and (2) large terminals which appear to synapse on clear vesicle terminals which in turn innervate body wall muscle cells. The clear vesicle ending resembles known cholinergic junctions in other systems. The cores in the dense core vesicle terminals are regarded as containing 5‐HT because (1) they are structurally identical with the 5‐HT containing cores in granules of the Retzius cells, (2) they contain a chromaffin substance, and (3) they become radioactive when tritiated 5‐HT is present but not when 5‐HTP or noradrenaline is present.
Atlas of estradiol‐concentrating cells in the central nervous system of the female rat
Authors: Pfaff Donald , Keiner Melvyn 
Published: May 2005

AbstractTwo hours following intraperitoneal injection, estradiol‐H3 is concentrated by cells in a system of limbic and hypothalamic structures. Preoptic‐hypothalamic nuclei containing estrogen‐concentrating cells include the medial preoptic area, medial anterior hypothalamus, ventromedial nucleus, arcuate nucleus and ventral premammillary nucleus. Limbic structures include the medial and cortical nuclei of the amygdala, lateral septum, bed nucleus of the stria terminalis, diagonal band of Broca, olfactory tubercle, ventral hippocampus, and prepiriform and entorhinal cortex. Labelled cells were also found in the lateral and ventrolateral portions of the mesencephalic central grey. Compared to these regions, most other regions of the nervous system, including the spinal cord, have very small numbers of labelled cells, which are relatively weakly labelled, and are not found in regular, specific locations. The distribution of estrogen‐concentrating cells determined with the present autoradiographic method agrees with previous autoradiographic conclusions and with biochemical results from cell fractionation experiments.The locations of estrogen‐concentrating cells coincide in several brain regions with locations of estrogen‐dependent neuroendocrine control mechanisms, as determined by brain implants, lesions, electrical stimulation, and electrophysiological recording. Moreover, experimental neuroanatomical studies have provided evidence for several pathways connecting regions which concentrate radioactive estradiol. Taken together, the evidence suggests a limbic‐hypothalamic system of estrogen‐concentrating neurons which participate in the control of mating behavior and of gonadotrophin release from the pituitary.
Neuroglial response to sciatic neurectomy. II. Electron microscopy,
Authors: Kerns James M. , Hinsman Edward J. 
Published: May 2005

AbstractThe response of oligodendrocytes, astrocytes, multipotential glia (MPG), and pericytes to sciatic neurectomy in young adult rats was studied by electron microscopy. Animals were perfused with aldehyde fixative at 2, 4, 7, and 14 days postoperative (dpo).Neuronal changes were slight and there was no apparent response in either oligodendrocytes or pericytes. Typical reactive changes observed in the astrocytes included an increase in glial filament bundles and microtubles. At 2 dpo mitotic cells were observed and by 4 dpo many MPG were located around affected neuron cell bodies apparently isolating them. The MPG processes formed overlapping sheets of processes between neurons and the elements of the neuropil. Hence synaptic boutons were displaced from the surfaces of the ensheathed neurons, but phagocytosis of synaptic boutons was rarely observed. The role and origin of the MPG and their similarity to microglia are discussed.
Mitral cell development in the mouse olfactory bulb: Reorientation of the perikaryon and maturation of the axon initial segment
Authors: Hinds James W. , Ruffett Trudy L. 
Published: May 2005

AbstractThe proximal portion of mitral cell axons was examined in electron microscopic serial sections and Golgi impregnations of mouse embryos on the fifteenth day of gestation (E15), E16, postnatal day one (P1), and P4. During this time the cell body of developing mitral cells appears to transform from tangential to radial orientation and then migrate peripherally while the tangential axon remains relatively fixed. In E15, E16 and P1 animals, electron microscopy of most radial mitral cells reveals that the microtubules of the axon proper are continued as a bundle of approximately the same diameter through the voluminous subnuclear cytoplasm to one side of the nucleus. The rest of the subnuclear cytoplasm is nearly devoid of microtubules and contains only free ribosomes and an occasional mitochondrion. It is suggested that the position of the axon is determined within the perikaryon by a bundle of microtubules; the nucleus and rest of the subnuclear cytoplasm then migrates peripherally leaving only a relatively thin axon. If some of the perikaryal cytoplasm failed to migrate peripherally, a bleb or process might be left, as in fact has been observed in Golgi impregnations and electron microscopy. We have also examined the ultrastructure of the developing axon initial segment, in cross‐sections of the axons from E15 to P4, as well as in longitudinal serial sections. Fascicles of closely apposed microtubules have been noted in some advanced mitral cells at E15 and E16, and by P1 such fascicles are common and well developed in most mitral cells. In P1 animals some mitral cell initial segments show a faint and patchy dense undercoating of the axolemma, but many axons at this time appear to completely lack this feature. By P4 nearly all initial segments show a fairly well developed dense undercoating. In general, therefore, the development of fascicles of closely apposed microtubules precedes the elaboration of the dense undercoating of the axolemma.
Transport of proteins across normal cerebral arterioles
Authors: Westergaard E. , Brightman M. W. 
Published: May 2005

AbstractPortions of certain arterioles on the surface of the brain and within it can transfer protein from blood to perivascular basement membrane. One to 50 mg of horseradish peroxidase (MW: 40,000) were injected intravenously into normal, adult mice. Three to 30 minutes later, their brains were fixed by vascular perfusion of aldehydes, incubated, and processed for electron microscopy.Segments of some cerebral arterioles, with an average diameter of 15‐30 μ, transported peroxidase. The pial arterioles were mainly situated within sulci, the parenchymal ones in the ventral part of the diencephalon and adjacent brain stem. The arteriolar segments were, commonly, bifurcations and short, straight portions. Similar vessels transferred protein in normal rats and hamsters. Neither increasing the dose of peroxidase above 10 mg nor the circulation time from 3 to 30 minutes altered the number of transferring vessels in mice.The endothelial cells were, as in cerebral capillaries, linked by tight junctions that prevented the extracellular passage of peroxidase. When peroxidase was injected 45 minutes after fixation, it did not reach the basement membrane. Moreover, ferritin, too large a molecule (MW: 900.000) to pass through these endothelial junctions, was also transported across the same segments 3 minutes after 100‐500 mg had been injected intravenously. These observations indicate that vesicular transport rather than passive, extracellular movement was the means of transferring proteins from blood to perivascular basement membrane. It is probable that serum albumin and globulins are likewise transferred in normal rodents.
Organization of cerebellar cortex secondary to deficit of granule cells in weaver mutant mice
Authors: Rakic Pasko , Sidman Richard L. 
Published: May 2005

AbstractThis study deals with some consequences of the early postnatal abnormalities of cerebellar Bergmann glial fibers and granule cell neurons. (1) Cerebellar size is mildly reduced in heterozygous weaver (+/wv) mice and markedly reduced in homozygotes (wv/wv), but the pattern of fissures is essentially normal. Comparison with other mutants displaying small cerebella suggests that cell proliferation rate in the external granular layer is a key deteminant of cerebellar cortical folding. (2) Mossy fiber terminals differentiate on schedule despite the reduced number and abnormal positions of granule cells. However, many of them enter the modified molecular layer, and as noted especially in noninbred wv/wv mice one to two years old, form synapses with dendrites of aberrant granule cells. Where granule cells are absent, mossy fibers form more than the normal number of synapses with dendrites of Golgi type II neurons. (3) Purkinje cells are only mildly affected by the disorder of neighbouring cells. Their dendrites grow abnormally into the territory occupied by external granule cells, reach the external surface, and may turn inward. They form few tertiary branches. Dendritic spines are present in profusion and show membrane thickenings akin to normal postsynaptic elements. Although they receive no axonal contacts, the spines persist, enveloped by glial processes, for at least two years. Apart from the absence of parallel fiber contacts, afferent and intrinsic axons form the normal classes of synaptic connections with Purkinje cells. (4) Interneurons of the molecular layer are generated on schedule. At the time of their earliest recognition, they reside in the external granular layer, where they receive synaptic contacts from climbing fibers and other interneurons. In the absence of parallel fibers, interneurons differentiate in situ but their dendrites are abortive and randomly oriented. Growth of their dendrites, in contrast to that of Purkinje cell dendrites, appears to be markedly influenced by the organization of the local cellular milieu.
Osmotic opening of tight junctions in cerebral endothelium
Authors: Brightman Milton W. , Hori Masaharu , Rapoport Stanley I. , Reese Thomas S. , Westergaard Erik 
Published: May 2005

AbstractHyperosmotic solutions of 3 M urea, either infused into one internal carotid artery or applied topically to the pia mater of rabbits, results in the opening of endothelial tight junctions through which horseradish peroxidase passes from blood to extracellular fluid of the brain. The evidence for this opening of the blood‐brain barrier to protein is the entry of peroxidase into the extracellular pools between successive tight junctions. In animals not receiving 3 M urea, the interjunctional pools are inaccessible to proteins. Having passed through the endothelial junctions, the peroxidase spreads along the extracellular channels of the perivascular neuropil for approximately 100 μ in 90 seconds. Most of the affected vessels are capillaries, though larger vessels are rendered leaky as well. Calyciform cisterns, that lie beneath shallow notches in the endothelium of untreated rabbits, appear to be enlarged after the administration of 3 m urea. It is undetermined whether these few endothelial cisterns and vesicles are involved in carrying protein from blood to the cerebral extracellular fluid.
Unmyelinated axons in the ventral roots of the cat lumbosacral enlargement
Authors: Coggeshall Richard E. , Coulter Joe Dan , Willis William D. 
Published: May 2005

AbstractThe ventral roots L7 and S1 of the cat spinal cord were examined with the light and electron microscopes. Differences in the morphology of Schwann cells associated with large myelinated fibers and with small myelinated or unmyelinated fibers were observed. The blood vessels were largely encircled by pericytes. The most noteworthy finding was that 29% of the axons in these roots were unmyelinated. These unmyelinated axons were greatly reduced in number proximal but not distal to a ventral rhizotomy. Furthermore, they were reduced in number following dorsal root ganglionectomy, but not after dorsal rhizotomy, sympathectomy or peripheral nerve section. It is concluded that the ventral roots of the lumbosacral enlargement contain a large population of unmyelinated fibers originating from dorsal root ganglion cells.
The anatomical organization of hindlimb motoneurons in the lumbar spinal cord of the frog, Rana catesbiana
Authors: Cruce William L. R. 
Published: May 2005

AbstractThe precise location of lumbar spinal motoneurons was studied in the bullfrog by observing the retrograde reaction following injury to nerves which innervate different hindlimb muscles. The results were confirmed and their usefulness for physiological studies was demonstrated by iontophoretically injecting dye through an intracellular recording micropipette into motoneurons which were identified by antidromic spike invasion. The effects of plexus variation upon the location of motoneuron pools was considered in order to standardize the results and make possible comparisons between different frogs.New determinations were made of frog hindlimb muscle function with reference to jumping in order to assess the possible functional significance of motoneuron organization. In general, motoneurons acting upon proximal joints are located rostrally to motoneurons acting upon distal joints and flexor motoneurons are located rostrally to extensors.The somatotopic significance of motoneuron organization was also assessed and it was found that within the lateral motoneuron column there are three groups of cells, each of which innervates different, but somatotopically related groups of muscles. This organization is quite similar to that found in cats. The developmental and functional implications of this similarity are considered.
Observations on the synaptic organization of the retina of the albino rat: A light and electron microscopic study
Authors: Leure‐Dupree Alphonse E. 
Published: May 2005

AbstractAn electron microscopic study of the retina of the albino rat, with particular emphasis on the synaptic organization of the inner and outer plexiform layers, has been correlated with specimens impregnated with a modified Golgi technique.The central element of the photoreceptor “triad” in the outer plexiform layer is a bipolar cell dendrite.Two types of synaptic contacts were observed in the inner plexiform layer, the “dyad” ribbon synapse and the conventional synapse. The postsynaptic elements of the “dyad” consisted of an amacrine process and a ganglion cell dendrite. Conventional synapses were made by amacrine processes which were usually presynaptic to bipolar terminals. Reciprocal synapses between processes making ribbon synapses and those making conventional synapses were seen.Golgi technique revealed the presence of two types of bipolar cells, three types of amacrine cells, and one type each of horizontal and ganglion cell.These findings are discussed in relation to reported receptive field organization.
Ascending connections of a thalamic auditory area in a crocodile, Caiman crocodilus
Authors: Pritz Michael B. 
Published: May 2005

AbstractNucleus reuniens pars centralis is the major recipient of the ascending auditory lemniscus from the midbrain in the crocodile, Caiman crocodilus. Its ascending connections were studied by means of the Fink‐Heimer procedure with the light microscope after anodal, stereotaxic lesions. Following unilateral destruction of nucleus reuniens pars centralis, degenerating axons assemble on the lateral aspect of the pars centralis, pass through the pars diffusa, and enter the dorsal peduncle of the lateral forebrain bundle. These fascicles travel rostrally in the lateral forebrain bundle where they remain restricted to the medial aspect of this tract. At more rostral levels, these degenerating axons turn dorsad, pass through and perhaps synapse on interposed neurons of the medial portion of the ventrolateral area, and end on cells located in the overlying dorsolateral area. This terminal field is composed of small, round, tightly packed neurons located in a medial caudal part of the dorsolateral area.This experiment together with a previous report demonstrates the existence of a specific and sharply localized auditory pathway leading from the central nucleus of the torus semicircularis by way of nucleus reuniens pars centralis to the telencephalon. The findings of this study are compared with similar research on thalamotelencephalic projections of diencephalic auditory areas in other amniotes.