bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of the spinal nerves of the larval lamprey: IV. Spinal nerve roots of 21‐mm larval and adult lampreys, with special reference to the relation of meninges with the root sheath and the perineurium
Authors: Nakao Taisuke , Ishizawa Akimitsu 
Published: January 2005

AbstractSpinal nerve roots of 21‐mm larval and adult lampreys were electron microscopically studied. In 21‐mm larval lampreys, each ventral and dorsal rootlet contains axons of various diameters enclosed together as groups in individual troughs of a Schwann cell cytoplasm, lying in direct contact with one another, and is further ensheathed entirely by a basal lamina. Dorsal roots possess visceral axons, while ventral roots lack them. In adult lampreys the ventral and dorsal roots possess individual sheaths for larger somatic axons, each being surrounded by a single Schwann cell and the basal lamina and separated from one another by a considerable amount of connective tissue. Visceral fibers are present in both the dorsal and ventral roots of adult lampreys. They aggregate to form fascicles that lie among somatic axons, being separated from them.Two layers of the meningeal tissue invaginate to form a root sheath around the distal portion of individual dorsal and ventral roots of 21‐mm larval lampreys. In adult lampreys the sheath is similarly formed but extends over most of the dorsal and ventral roots. The perineurium is not developed in 21‐mm larval lampreys, but is present and ensheaths only the proximal portion of spinal nerve trunks outside the meninges in adult lampreys: it is completely absent along most of the length of peripheral nerves. In both larval and adult lampreys, the outer cell layer of the root sheath is open‐ended near the middle of nerve roots with respect to the extramedullary connective tissue space. Similar loosening of the cellular barrier is seen along blood vessels. Thus, the outer meningeal fibrous layer is directly continuous with the extra medullary connective tissue space by way of the inner fibrous layer of the root sheath.
Autoradiographic study of descending pathways from the pontine reticular formation and the mesencephalic trigeminal nucleus in the rat
Authors: Sirkin David W. , Feng Albert S. 
Published: January 2005

AbstractDescending projections were studied in autoradiographically prepared material after injections of tritiated leucine in the pontine tegmentum of rats. Injections involving the medial pontine reticular formation resulted not only in labeling commissural fibers, the medial reticulospinal tract, and the dorsal cap of the inferior olive, but also, in two cases, in labeling a cerebellar projection that originated from a region near the midline and clearly dorsal to the nucleus reticularis tegmenti pontis. The labeled fibers passed ventrad in the midline to the pontine gray, then laterally through the gray and into the middle cerebellar peduncle to terminate as mossy fibers primarily in the flocculus, lobulus simplex, and Crus I of the ansiform lobule.Injections involving the mesencephalic nucleus of the trigeminal nerve (Vmes), resulted in labeling of Probst's tract, which descends in the dorsolateral reticular formation. Probst's tract gave off extensive terminal branches to the lateral medullary reticular formation and weaker projections to restricted portions of the descending trigeminal nucleus, the solitary nucleus, and the hypoglossal nucleus. In one case, fibers could be traced into the dorsal horn of the upper cervical cord.
Morphology and distribution of the projection neurons in the cerebellum in a teleost, Sebastiscus marmoratus
Authors: Murakami Takeshi , Morita Yasuhiro 
Published: January 2005

AbstractCerebellar efferent neurons in a teleost, Sebastiscus marmoratus, were studied by means of the horseradish peroxidase (HRP) tracing and Golgi impregnation methods. The cerebellar efferents or eurydendroid neurons are classified into two types (A and B) on the basis of the morphology of the dendrites, intracerebellar distribution, and other afferent connections. Type A neurons form a cell cluster in the lobus caudalis and have one thick primary dendrite from which several branches with sparse but long spines extend into the molecular layer of the lobus caudalis. Type B neurons, observed in both the valvula and corpus cerebelli, have two or three primary dendrites running along the ganglion cell layer, and the distal dendritic branches are distributed in molecular layer perpendiculary to the cerebellar surface. Small spines are densely studded on the dendrites of type B neurons. Somata of type A and B neurons are located in and just beneath the ganglion cell layer.The cerebellum projects to the ipsilateral nucleus lateralis valvulae and torus longitudinalis and bilaterally, but mostly contralaterally to the nucleus ventromedialis thalami of Schnitzlein ('62), nucleus ruber, the vicinity of the oculomotor complex, torus semicircularis, and brainstem reticular formation. Type A neurons send axons primarily to the vicinity of the oculomotor complex and partly to the nucleus ventromedialis thalami and the nucleus ruber, whereas type B cells project to all main cerebellar targets. In addition, type B cells are organized topographically in the cerebellum in relation to the efferent targets in the brainstem.
Relationships between ganglion cell dendritic structure and retinal topography in the cat
Authors: Schall J. D. , Leventhal A. G. 
Published: January 2005

AbstractThe morphology of ganglion cell dendritic trees varies across the cat retina. Evidence is presented that the variation in two attributes of ganglion cell dendritic structure can be accounted for by specific aspects of the topography of the adult and developing retina.The first attribute considered was the displacement of the center of the dendritic field from the cell body in the plane of the retina. The results of this study provide evidence that most ganglion cell dendritic fields are displaced away from neighboring cells, i.e., down the retinal ganglion cell density gradient. Because of the systematic dendritic displacement locally, the centers of the dendritic fields are arranged in a more precise mosaic than are their cell bodies.The second attribute considered was the elongation and orientation of the dendritic fields. From approximately embryonic day 50 to postnatal day 10 the cat retina undergoes a process of maturation (reviewed by Rapaport and Stone: Neuroscience 11:289–301, '84) that begins at the area centralis and spreads over the retina in a horizontally elongated wave. We found that the elongation and orientation of retinal ganglion cell dendritic fields is significantly correlated with the shape of the wave of maturation. The orientation of a dendritic field is not predicted by the direction of its displacement nor is it directly related to the distribution of neighboring retinal ganglion cells.These results indicate that the displacement of a ganglion cell's dendritic field from its cell body results from mechanisms different from those responsible for the orientation of the dendritic field. Factors that may be responsible for these two attributes of ganglion cell dendritic morphology are discussed.
Ganglion cell dendritic structure and retinal topography in the rat
Authors: Schall J. D. , Perry V. H. , Leventhal A. G. 
Published: January 2005

AbstractThe dendritic field size, the distribution of the dendrites relative to the cell body, and the overall shape of the dendritic field of type I ganglion cells in the rat retina were analyzed. These features of neuronal structure were related to the topography of the rat retina. As in the cat, the cell bodies of type I ganglion cells are arranged in a nonrandom mosaic. Previous work has demonstrated that the density of type I cells in the rat retina does not covary with the density of all ganglion cells. Type I dendritic field size varies over the retina; the increase in dendritic field size is accounted for better by the decrease in type I density than by the decrease in overall ganglion cell density. The center of the dendritic field of most type I cells is displaced in the plane of the retina from the cell body. Unlike in carnivore retina (Schall and Leventhal: J. Comp. Neurol. 257:149–159, '87), the dendritic fields in the rat are not displaced down the ganglion cell density gradient. Rather, there is a tendency for the dendritic trees, especially in temporal retina, to be displaced toward dorsal retina. Most of the dendritic fields are elongated, but the degree of elongation is less than that observed in carnivore or primate retina. Unlike in carnivore and primate retina (Leventhal and Schall: J. Comp. Neurol. 220:465–475, '83; Schall et al.: Brain Res. 368:18–23, '86), there is no relationship between dendritic tree orientation and position relative to any point on the retina in the rat. The foregoing differences in the morphology of retinal ganglion cell dendritic trees in rat, carnivore, and primate are considered in light of the differences in the development of retinal topography in these species.
A Golgi study of the monkey paraventricular nucleus: Neuronal types, afferent and efferent fibers
Authors: Rafols José A. , Aronin Neil , Difiglia Marian 
Published: January 2005

AbstractThe neuronal organization of the paraventricular nucleus (PVN) was examined in Golgi impregnations of adult monkey. Results showed that at least six types of neurons could be identified in the nucleus on the basis of morphological features of the somata, dendrites, and axons. Four types of neurons with sparse to densely spined cell bodies and dendrites exhibited long axons and included large neurons (types I and II), medium‐sized to large neurons (type III), and small to medium‐sized cells (type IV). Axons of type I, III, and IV neurons had different diameters and were followed out of the PVN. Axon collaterals that arborized within the PVN were seen on the axons of types III and IV cells. Two types of interneurons with small somata were also found. One (type V) exhibited varicose dendrites and a profusely arborizing local axon. The other cell (type VI) had recurved dendrites with long appendages and no impregnated axon. Afferent fibers were also identified. Type 1 was a fine‐caliber axon that coursed long distances in the PVN and exhibited numerous short branches. Additional observations suggested that type 1 afferents originated from the stria terminalis. The other afferent axon (type 2) was thicker and gave rise to terminal arborizations containing clusters of small swellings.The efferent fibers of the > PVN were also examined in impregnations of the paraventriculosupraopticohypophysial tract. Fibers formed an extensive plexus as they coursed ventrally and passed through the lateral hypothalamus. Axons coursing more laterally in the tract were much larger than those more medially located.Our findings show a diverse organization of neuronal types within the monkey PVN with evidence for intrinsic connections through axon collaterals of efferent neurons and the locally arborizing axons of interneurons. Correlations are proposed between morphological subtypes of neurons seen in this Golgi study and the known functional output pathways of the PVN.
The serotoninergic fibers in the dorsal lateral geniculate nucleus of the cat: Distribution and synaptic connections demonstrated with immunocytochemistry
Authors: De Lima Ana Dolabela , Singer Wolf 
Published: January 2005

AbstractThe distribution, morphology, and synaptic contacts of serotoninergic fibers were studied with immunocytochemical methods in the lateral geniculate complex of the cat. The serotonin‐immunoreactive fibers are diffusely distributed throughout the main laminae of the dorsal lateral geniculate nucleus (dLGN) and the perigeniculate nucleus (PGN) and reach a particular density in the ventral lateral geniculate nucleus (vLGN). The labeled fibers are in most cases very thin and sometimes varicose. There is no obvious order in their distribution pattern except that they sometimes partially encircle the unlabeled cell bodies of the dLGN.The synaptic connections of the serotoninergic fibers were investigated mainly in the A laminae of the dLGN. Few synaptic complexes were found, most of them with asymmetric morphology. The postsynaptic elements were small dendritic profiles. Perisomatic serotoninergic fibers were seen, but no convincing synaptic contacts were found between labeled fibers and cell somata. In the dLGN, serotoninergic profiles were almost exclusively confined to the extraglomerular neuropile. In the PGN serotoninergic fibers also contacted dendritic profiles and formed asymmetrical synapses, but as in the geniculate, synaptic specializations were very rare.
Intra‐axonal labeling of saccular afferents in the goldfish, Carassius auratus: Correlations between morphological and physiological characteristics
Authors: Sento Seishiro , Furukawa Taro 
Published: January 2005

AbstractLucifer yellow was used to label axons of 32 physiologically defined SI afferent fibers and 23 physiologically defined S2 afferent fibers of the goldfish sacculus. Analysis of these labeled fibers allowed us to study the relationship between electrical activity in these primary neurons and the morphology of their peripheral arborizations in the sensory macula. Morphological characteristics were highly indicative of response type: The peripheral arborizations of individual S1 fibers occupied a relatively small region (approximately 40 μm in diameter) in the rostral one‐fourth of the saccular macula, whereas those of individual S2 fibers covered a larger area (roughly 80 μm across) in the caudal part of the macula. In addition to this rostrocaudal dimension, a ventral projection was related to a rarefaction response, a dorsal projection was related to a compression response, and a two‐sided innervation was related to fibers having both responses. S1 fibers had either large or small terminals; the S2 fibers had only small terminals. On average, S1 fibers gave rise to approximately four terminals (e.g., seven small terminals or one to two large terminals) and S2 fibers approximately ten terminals. Spontaneous discharges were absent in all S1 fibers but present in some S2 fibers. Such S2 fibers showed spontaneous activity of either an irregular type or a burst type. In these, there was a tendency for fibers having more extensive arborizations to exhibit a burst type of spontaneous discharge. We conclude that structure‐function relationships can be determined for these primary neurons.
Patterns of cell death in the ganglion cell layer of the human fetal retina
Authors: Provis Jan M. 
Published: January 2005

AbstractThe distribution of dying cells in the ganglion cell layer (GCL) of retinae from human fetuses has been analysed. Both whole‐mounted and sectioned retinae have been studied. Results suggest that cells are lost from the GCL between weeks 14 and 30 of the gestation period, approximately. This period corresponds to the period during which axons are lost from the developing optic nerve. Cell loss is greatest between weeks 16 and 21 of the gestation period. The pattern of cell loss is nonuniform, and between weeks 16 and 24, the relative frequency of pyknotic cells (pyknotic cells: viable cells) in peripheral retina is considerably higher than in central retina. This pattern of cell loss predominates during the period in which a distinct centroperipheral gradient of cell densities emerges in the GCL of the human fetal retina (between 18 and 23 weeks gestation). It is suggested that the regional loss of ganglion cells may contribute to the formation of the cell density gradient.
GABAergic nonpyramidal neurons in intracerebral transplants of the rat hippocampus and fascia dentata: A combined light and electron microscopic immunocytochemical study
Authors: Frotscher Michael , Zimmer Jens 
Published: January 2005

AbstractGlutamate decarboxylase (GAD) immunocytochemistry was used to study GABAergic neurons and synapses in intracerebral allografts of the rat hippocampus and fascia dentata. Tissue blocks of regio inferior of Ammon's horn (hippocampal field CA3) or of the fascia dentata were taken from newborn rats and transplanted to the hippocampal region of young adult rats. After 6 1/2 months' survival the recipient brains were fixed by perfusion and serially sectioned on a Vibratome. Sections containing the transplant and/or the host hippocampal region were immunostained for GAD and flat‐embedded in Araldite for a correlated light and electron microscopic analysis. Immunostained neurons and terminals in the transplants were compared to immunoreactive elements in the hippocampus and fascia dentata of the hosts and other, normal rats.As in the hippocampal formation in situ, GAD‐immunoreactive neurons and terminals in the transplants were observed in all layers. In dentate transplants a preponderance of immunostained cells was found just beneath the granule cell layer. In both hippocampal and dentate transplants, immunoreactive terminals were most abundant in the cell layers where they formed characteristic pericellular baskets around the pyramidal and granule cell bodies.In the electron microscope, the transplant GAD‐immunoreactive neurons exhibited numerous cytoplasmic organelles, deeply infolded nuclei, and nuclear rods. Immunoreactive terminals formed symmetric synaptic contacts on the cell bodies, dendritic shafts, and spines of transplant pyramidal cells, granule cells, and hilar neurons. These are normal characteristics of GAD‐immunoreactive neurons and terminals as also observed in the hippocampus of the host rats and the normal controls.Our results demonstrate that GABAergic neurons survive transplantation and develop a cell‐specific morphology that includes the axonal projections.
The peripheral distribution and central projections of the sensory rami of the facial nerve in goldfish, Carassius auratus
Authors: Puzdrowski R. L. 
Published: January 2005

AbstractTaste buds in goldfish and other cyprinids are found not only within the oropharyngeal cavity but also scattered over the external body surface. The external taste buds are innervated by branches of the facial nerve that terminate centrally in an enlargement of the medulla termed the facial lobe. The peripheral distribution and areas of innervation of the rami of the facial sensory nerve were determined by using a modification of the Sihler technique and by examination of a Bodian‐stained head series. The central projections of individual rami of the facial sensory nerve were traced by means of the horseradish peroxidase (HRP) technique.Fibers of the facial sensory nerve distribute over the head and trunk via nine rami. The supraorbital ramus distributes fibers to taste buds above the eye. The palatine, maxillary, and mandibular rami innervate taste buds of the rostral palate, upper lip, and lower lip, respectively. The three rami of the hyomandibular trunk innervate taste buds on the operculum, branchiostegal rays, and in the lower cheek region. A facial recurrent ramus was also found that distributes fibers to taste buds on the trunk and pectoral fin via two rami, the lateral recurrent ramus and pectoral recurrent ramus.The facial sensory rami map somatotopically on the facial lobe. Overall, the projections follow an anteroposterior orientation with the long axis of the body tilted slightly ventrally. The lips and rostral palate make up a disproportionately large portion of the map, taking up nearly the entire ventral extent of the lobe. The trunk and pectoral fin regions map broadly across the dorsal portion of the lobe. Further, projections to the nucleus of the descending trigeminal tract were observed with labeling of the supraorbital, maxillary, and mandibular rami, and the rami of the hyomandibular trunk. Projections to the facial motor nucleus were also observed with labeling of maxillary and mandibular rami, perhaps indicating a monosynaptic reflex arc. These projections have not been reported in previous studies on the teleostean facial taste system.
Accessory optic system of an anthropoid primate, the gibbon (Hylobates concolor): Evidence of a direct retinal input to the medial terminal nucleus
Authors: Cooper H. M. , Magnin M. 
Published: January 2005

AbstractThe accessory optic system (AOS) was studied in an anthropoid primate by using anterograde transport of tritiated amino acids and autoradiographic techniques. The course of the accessory optic tract (AOT) and the retinal projection to the terminal nuclei are described in the gibbon and compared to that of other mammals.The AOT consists of a superior fasciculus, which includes both an anterior and a posterior fiber branch. An inferior fasciculus of the AOT is absent. In contrast to previous reports in haplorhine primates, which describe the AOS as consisting of only the dorsal (DTN) and the lateral (LTN) terminal nuclei, we find that in the gibbon, three cellular groups receive a bilateral projection, predominantly from the contralateral retina. According to cytoarchitecture and topographic location, two of these nuclei correspond to the DTN and the LTN. The third cellular group, situated dorsomedial to the substantia nigra, receives a distinct retinal projection and extends rostrocaudally for 2.0 mm in the mesencephalon. This nucleus is homologous to the dorsal division of the medial terminal nucleus (MTN) in other mammals. There was no evidence for a ventral division of the MTN, which in nonprimates is typically situated at the ventromedial base of the cerebral peduncle.Examination of brain morphology in primates suggests that the ventral division of the MTN has been displaced from its phylogenetically stable location in the medial part of the ventral midbrain to a more dorsal position. This shift appears to be a consequence of the overall morphological influences resulting from the relative enlargement of the pons in this region. The demonstration of a direct retinal projection to the MTN in the gibbon, as well as recent reports in other primates, indicates that a complete AOS consisting of three terminal nuclei is a feature common to all mammals.