bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sprouting in the avian brainstem auditory pathway: Dependence on dendritic integrity
Authors: Rubel Edwin W. , Smith Zaid D. J. , Steward Oswald 
Published: May 2005

AbstractThe brainstem auditory pathways of the chicken were used to examine the relationship between the maintenance of dendrites following de‐nervation and the successful reinnervation (sprouting) by surviving afferents. In the system the third‐order cells in n. laminaris receive spatially segregated bi‐naural innervation from n. magnocellularis. Afferents from the ipsilateral n. magnocellularis innervate the dendrites on the dorsal aspect of n. laminaris cells, while afferents from contralateral magnocellular neurons innervate ventral den‐drites via the crossed dorsal cochlear tract. Denervation of the ventral dendrites of n. laminaris cells by transection at the midline results in rapid and severe atrophy of the denervated dendrite. Unilateral cochlea removal induces tran‐sneuronal degeneration of 30–45% of the ipsilateral magnocellular cells, thereby partially denervating one dendrite of the n. laminaris cells on each side of the brain.In animals with long‐standing transections of the crossed dorsal cochlear tract there is no evidence of sprouting of fibers from the ipsilateral n. magnocellularis when the projections of the surviving magnocellular neurons are traced with degeneration methods after a secondary cochlea removal. However, when den‐drites of n. laminaris are partially denervated dendrites do not disappear. Fur‐thermore, secondary lesions of the crossed dorsal cochlear tract or secondary cochlea removal reveal that these denervated dendrites are reinnervated by the afferents from the opposite n. magnocellularis which are normally restricted to the opposite dendrite of the n. laminaris cells.
Comparative study of the posterior red nucleus in baboons and gibbons
Authors: Padel Y. , Angaut P. , Massion J. , Sedan R. 
Published: May 2005

AbstractThe posterior red nucleus (PRN) was studied in two species of primates by the technique of retrograde degeneration of rubrospinal cells following transection of the spinal cord at different levels. The form of the PRN was reconstructed for both a quadruped monkey (baboon) and an anthropoid with erect posture (gibbon). The PRN contains polymorphic cells characterized by their very chromophilic and granular NIssl substance. These neurons vary in diameter from 25 μm to 70 μm. Some of them give rise to the rubrospinal tract.Baboon: The approximately 1,300 rubrospinal cells in this species are divided into two equal groups, one related to the contralateral forelimb, with axons ending between the second cervical and third thoracic segment, and the otehr related to the contralateral hindlimb, projecting caudally beyond T3. Following a high cervical lesion, nondegenerated cells of similar description remain throughout the nucleus. A significantly large group of these cells occurs medially and may be the source of fibers ending in the brain stem or cerebellum.Gibbon: In this species, the number of rubrospinal cells controlling the hindlimb is less than half that found in the baboon. This reduction in the gibbon is much greater for medium‐sized cells, but is also significant for the giant cells.These results obtained from primates are compared with those reported for the cat. A possible function for the PRN in the control of limb movements is discussed from the viewpoint of phylogeny.
Transplantation of tectal tissue in rats. II. Distribution of host neurons which project to transplants
Authors: Harvey Alan R. , Lund Raymond D. 
Published: May 2005

AbstractTectal tissue was dissected from fetal rats and transplanted adjacent to the superior colliculus of newborn rats. The recipient animals were then allowed to survive for 6 or more weeks. Subsequent examination revealed that the transplants generally lay over the host inferior colliculus and rostral part of the cerebellum and had substantial fiber connections with the host superior colliculus. To determine which host areas projected to the transplants, horseradish peroxidase (HRP) was injected into the transplants, and the host brain was examined for the presence of retrogradely filled neurons.Labeled cells were found in nearly 50 host areas. Most of these areas are known to project to normal superior colliculus. There was a consistency between one animal and another in the frequency and density of cell label in the various areas. The projection from host cortex (particularly from visual cortical areas) was the densest and most consistent projection. Other areas which commonly projected into the transplants included pretectum, parabigeminal nucleus, superior colliculus, and the brachial region of the inferior colliculus. Sparse and infrequent projections were found from ventral lateral geniculate nucleus, substantia nigra, zona incerta, and catecholaminergic nuclei. No unequivocally labeled retinal ganglion cells were found.The results indicate that the host projection into the transplants is limited to those areas with axons in the vicinity of the host/transplant interconnection. However, the data also suggest that (1) the relative maturity of particular host pathways at the time of transplantation and (2) some form of preferential or absolute affinity expressed between host axons and transplant cells are also factors which influence the pattern of connections formed between host and transplant.
Lectin receptors on cells isolated from the turtle retina
Authors: Sarthy P. Vijay , Bridges C. David , Kretzer Francis L. , Lam Dominic M. K. 
Published: May 2005

AbstractThe presence of specific oligosaccharides on the surface of retinal cells was examined by incubating FITC‐labeled lectins with cells dissociated from papain‐treated turtle retinas. The pattern and intensity of binding was found to vary among the cells examined. With Con A, there was strong surface staining of both rods and cones, with an intense ring of fluorescence above the nucleus. The bipolar and ganglion cells also showed strong surface labeling. In Müller (glial) cells there was intense fluorescence in the apical, microvillous region. In contrast, the horizontal cells and their axons showed weak staining. When RCA‐60, RCA‐120, and WGA were incubated with photoreceptors, bipolar cells, or horizontal cells, little fluorescence was visible. However, all three lectins bound strongly to the Müller cells. In contrast, the Lotus lectin did not bind to any of the cells examined. In all the cases, lectin binding was inhibited by the appropriate haptene sugar. Further, prior treatment of cells with neuraminidase did not alter lectin binding to any cell type. These results suggest differences in the distribution of lectin receptors among specific cell types, and particularly between neurons and glial cells in the vertebrate retina.
Histopathological reactions and axonal regeneration in the transected spinal cord of hibernating squirrels
Authors: Guth Lloyd , Barrett Charles P. , Donati Edward J. , Deshpande Sharad S. , Albuquerque Edson X. 
Published: May 2005

AbstractThe failure of axonal regeneration in the transected spinal cord of mammals has been attributed to many factors, including an intrinsic lack of regenerative capacity of mature CNS neurons, mechanical obstruction of axonal elongation by glial‐connective tissue scars, necrosis of spinal tissue resulting in cavitation, lack of trophic influences sufficient to sustain outgrowth, and contact inhibition resulting from the formation of aberrant synapses. Assessment of the relative importance of each of these factors requires animal models in which one or more of these pathological processes can be eliminated. We therefore examined the effects of spinal transection in the hibernating animal because, during hibernation, collagen formation is depressed while nerve regeneration and slow axonal transport are maintained. Midthoracic spinal transections were performed in hibernating ground squirrels and the spinal cords were examined histologically 1–6 months later. The lesion site was composed primarily of a loose accumulation of macrophages and showed minimal glial and collagenous scarring, or cavitation. There was extensive regeneration of intrinsic spinal cord and dorsal root fibers. These axons grew to the margin of the lesion where they turned abruptly and continued growing along the interface between the lesion and the spinal cord. We conclude (1) that mammalian spinal‐cord neurons have considerable regenerative potential; (2) that such mechanical impediments as collagenous and glial scarring, cyst formation, and cavitation cannot provide the sole explanation of why regeneration in the mammalian CNS is abortive; and (3) that specific physical and chemical properties of the cells in the environment of the growth cone regulate the extent and orientation of regenerative axonal outgrowth.
Identification and localization of the motor nuclei and sensory projections of the glossopharyngeal, vagus, and hypoglossal nerves of the cockatoo (Cacatua roseicapilla), cacatuidae
Authors: Wild J. Martin 
Published: May 2005

AbstractHorseradish peroxidase (HRP) has been applied to the proximal severed ends of glossopharyngeal (NIX), vagus (NX), and hypoglossal (N XII) cockatoo in order to localize the motoneurons and sensory projections of these nerves which are involved in the control of the bird's feeding and phonatory behaviors.Application of HRP to N IX labeled four rhombencephalic nuclei: (1) a largecelled, retrofacial nucleus supplying M. geniohyoideus, the major tongue extensor; (2) a dorsal nucleus composed of medium‐sized cells, projecting to most branches of N IX; (3) a ventrolateral nucleus supplying, amongst other structures, the floor of the pharynx and larynx; and (4) a ventral portion of the dorsal motor nucleus of the vagus.Neurons labeled by application of HRP to the cervical vagus comprise the classically defined dorsal motor nucleus and a ventrolateral medullary nucleus which is coextensive with that of the glossopharyngeus: together they probably constitute a nucleus ambiguus.Application of HRP to hypoglossal branches labeled a large nucleus intermedius (IM) and neurons ventral, ventrolateral, and caudal to it. The rostral third of IM supplies the lingual muscles, the caudal two‐thirds the tracheosyringeal muscles.Many labeled neurons were found in the “jugular” ganglion following HRP treatment of each of the three nerves, especially N IX and N XII, which innervate the tongue. Central projections of these neurons are to nuclei of the descending trigeminus and to largely nonoverlapping portions of the principal trigeminal nucleus. It is hypothesized that these afferents provide sensory information necessary for the efficient processing and passage of food in the mouth.
Laminar organization of the afferent and efferent systems of the torus semicircularis of Gymnotiform fish: Morphological substrates for parallel processing in the electrosensory system
Authors: Carr C. E. , Maler L. , Heiligenberg W. , Sas E. 
Published: May 2005

AbstractThe torus semicircularis of Gymnotiform fish is an enlarged laminated midbrain structure which receives lemniscal input from electrosensory, mechanoreceptive lateral line, and auditory systems. The electrosensory input is confined to the dorsal torus, while the auditory and mechanoreceptive systems project to the ventral torus. Anterograde and retrograde techniques were used to determine the connections of the dorsal torus in Apteronotus and Eigenmannia. The dorsal torus can be divided into nine major laminae, each of which has distinct afferent and efferent connections. The dorsal torus receives five afferent inputs: (1) A contralateral topographic input from the posterior lateral line lobe (PLLL) projects to laminae III, V, VI, VII, VIIIB, and VIIID. (2) Eurydendroid cells of the caudal lobe of the cerebellum project contralaterally to lamina VIIIB. (3) A portion of the descending nucleus of V projects to laminae VIIIA, VIIIC, and IX. (4) Lamina I is a cap of fine myelinated fibers which may originate in the torus longitudinalis. They project to laminae II and III. (5) The ipsilateral optic tectum projects to the dorsal torus. The dorsal torus projects to six major targets: (1) Laminae VII, VIII, and IX project bilaterally to a lateral region of the diencephalon above n. preglomerulosus, herein named n. electrosensorius. An area below the dorsal thalamus receives a smaller ipsilateral projection. (2) Laminae II, V, VIvn, VII, VIII, and IX project topographically to the deeper laminae of the ipsilateral optic tectum. This projection is in spatial register with the visual map in the superficial layers of the tectum. (3) Lamina VIIID projects ipsilaterally to the lateral reticular formation. (4) All laminae other than I, VI, and VIIIB project topographically to the ipsilateral n. praeeminentialis, which provides a powerful descending projection to the PLLL. (5) Lamina IX projects to a dorsal pretectal area. (6) The ipsilateral inferior olive receives a projection from the dorsal torus.
Branching of sensory axons in the peripheral nerve of the rat
Authors: Langford Lauren A. , Coggeshall Richard E. 
Published: May 2005

AbstractThe currently accepted concept of a primary sensory cell is a cell that gives rise to a central process which passes through the dorsal root to the spinal cord and a peripheral process which passes to the periphery via a peripheral nerve. If this is correct, then there should be equal numbers of sensory axons in the dorsal root, dorsal root ganglion cells, and sensory axons in the proximal peripheral nerve. The present study obtains these counts in animals in which extraneous axons have been removed from the peripheral nerve and root. The counts indicate that there are approximately 2.3 sensory axons in the dorsal root and proximal peripheral nerve for each ganglion cell in the sacral segments of the rat. We interpret these data as indicating that there is significant branching of sensory axons in the dorsal root and proximal peripheral nerve and thus the generally accepted picture of a dorsal root ganglion cell is not correct for some, perhaps all, of these cells. We offer the speculation that this peripheral branching may be an indication of single sensory neurons having receptive fields in two separate locations, and thus this may be an anatomical explanation for certain types of referred pain.
Intercellular junctions in the developing arachnoid membrane in the chick
Authors: Van Rybroek John J. , Low Frank N. 
Published: May 2005

AbstractThe arachnoid membrane of chick embryos was prepared for electron microscopic study by means of thin sections and freeze‐fracture replicas. Particular attention was given to the relationships among junctional complexes during arachnoid maturation. By 14 days of incubation, the arachnoid had differentiated into morphologically distinct inner and outer zones. Both desmosomes and gap junctions were present among the cells of both layers at this time. Desmosomes were most numerous in the inner arachnoid layer and their structure remained constant. Gap junctions showed a great variation in structure. The large gap junctions contained a particle packing pattern in which rows of intramembranous particles were separated by particle‐free zones. Arched gap junctions were also present. Smaller arrays of gap junctions exhibited a variety of configurations on the membrane P‐face. The first tight‐junctional strands clearly identifiable in freeze‐fractured preparations appeared at 15–17 days. These were closely associated with the particles of gap junctions and consisted of single strands on the P‐face. By hatching age (21 days) a “mature” pattern of tight‐junctional strands was interwoven in several layers. In the interim, more complex arrangements of tight‐junctional strands were in intimate relation with gap junctions.
Localization of synaptic and nonsynaptic nicotinic‐acetylcholine receptors in the goldfish retina
Authors: Zucker Charles , Yazulla Stephen 
Published: May 2005

AbstractThe localization of nicotinic‐cholinergic receptors in the inner plexiform layer (IPL) of goldfish retina was studied by electron microscopic analysis of the binding pattern of a conjugate of horseradish peroxidase and αbungarotoxin (HRP‐αBTx). Specific HRP reaction product (blockable by 1mm curare) was found at both synaptic and nonsynaptic sites. Synaptic binding sites for HRP‐αBTx, which accounted for only 16% of the total specific reaction product sites, always involved an amacrine process as the presynaptic element, whereas amacrine, ganglion, and bipolar cells could be postsynaptic elements at labeled synapses. Only 17.5% of the total number of amacrine synapses were labeled by HRP‐αBTx. Labeled synapses showed the same distribution in the IPL as unlabeled synapses: bimodal for amacrine‐to‐bipolar synapses with peak concentrations at the 20% and 80% layers and unimodal for amacrine‐to‐nonbipolar synapses with a peak concentration at the 60% layer. Nonsynaptic binding sites for HRP‐αBTx (84% of total) were seen on the dendrites of ganglion, amacrine, and bipolar cells. The distribution of the nonsynaptic sites in the IPL largely accounts for the trilaminar binding pattern of 125I‐αBTx as observed in light microscopic autoradiographs. If, as appears likely, the distribution of synapses is the relevant variable in determining the sites of neuronal interaction for a given transmitter system, then this study further illustrates the importance of distinguishing synaptic from nonsynaptic binding when using receptorligand probes to localize sites of chemical synaptic transmission.
Intrinsic connections and architectonics of posterior parietal cortex in the rhesus monkey
Authors: Pandya Deepak N. , Seltzer Benjamin 
Published: May 2005

AbstractBy means of autoradiographic and ablation‐degeneration techniques, the intrinsic cortical connections of the posterior parietal cortex in the rhesus monkey were traced and correlated with a reappraisal of cerebral architectonics. Two major rostral‐to‐caudal connectional sequences exist. One begins in the dorsal postcentral gyrus (area 2) and proceeds, through architectnic divisions of the superior parietal lobule (areas PE and PEc), to a cortical region on the medial surface of the parietal lobe (area PGm). This area has architectonic features similar to those of the caudal inferior parietal lobule (area PG). The second sequence begins in the ventral post/ central gyrus (area 2) and passes through the rostral inferior parietal lobule (areas PF and PFG) to reach the caudal inferior parietal lobule (area PG). Both the superior parietal lobule and the rostral inferior parietal lobule also send projections to various other zones located in the parietal opercular region, the intraparietal sulcus, and the caudalmost portion of the cingulate sulcus. Areas PGm and PG, on the other hand, project to each other, to the cingulate region, to the caudalmost portion of the superior temporal gyrus, and to the upper bank of the superior temporal sulcus. Finally, a reciprocal sequence of connections, directed from caudal to rostral, links together many of the above‐mentioned parietal zones. With regard to the laminar pattern of termination, the rostral‐to‐caudal connections are primarily distributed in the form of cortical “columns” while the caudal‐to‐rostral connections are found mainly over the first cortical cell layer.
A quantitative analysis of changes in the olfactory epithelium following bulbectomy in hamster
Authors: Costanzo Richard M. , Graziadei Pasquale P. C. 
Published: May 2005

AbstractContinuous replacement of sensory neurons is a normal process in the olfactory system of adult vertebrates. The capacity for replacement following experimentally induced degeneration of sensory neurons makes this system ideal for the study of the dynamics of neural populations. A quantitative analysis was made to determine the time course and degree of cell replace‐ment in the olfactory epithelium following unilateral bulbectomy in adult hamsters. Histological measurements of number of cells and epithelial thickness were made for up to 194 days postoperatively. Results for each experimental animal were expressed as a percentage of the contralateral control side. There was an immediate degeneration of cells, the number decreasing to 39% by day 4. During days 4–15 new growth resulted in an increase in cell number, which was maintained at a level of 60–70% through day 194. Epithelial thickness decreased to 60–70% during the degeneration period, but there was no recovery during subsequent days 4–194. Analysis of epithelial cells by cell type (supporting, receptor, and basal cells) showed that changes in cell numbers were limited to the neural cell populations (receptor and basal). This study confirms that olfactory sensory neurons are capable of replacement following degeneration in spite of the absence of normal target tissue. However, the observed recovery does not reach control levels and the functional capacity of replacement neurons requires further study.
Comparative study of the glial fibrillary acidic protein in vertebrates by PAP immunohistochemistry
Authors: Onteniente Brigitte , Kimura Hiroshi , Maeda Toshihiro 
Published: May 2005

AbstractGlial fibrillary acidic protein (GFA) has been visualized by direct peroxi‐dase antiperoxidase (PAP) immunohistochemistry in various vertebrates (cyclostomes, teleosts, amphibians, reptiles, birds, and several placental mammals). In this study GFA‐immunoreactivity (GFA‐I) was observed in all species examined except in cyclostomes and amphibians. Two types of immunoreactive elements were observed: astrocytes and long processes without visible somata.Astrocytic cells with GFA‐I were first found in the snake, and more cells were in birds where the pattern of distribution was similar to that of mam‐mals. Within mammals, few differences in the manner of localization were observed among different species, except in the corpus callosum and the ependymal and subependymal layers.Long straight processes were observed in the lower submammalians‐ the lamprey, carp, and turtle. They radiated through the neuropil from the ventricular wall and followed nerve fiber bundles in the white matter. An un‐common feature was observed in the turtle brain, which possessed very in‐tense GFA‐I within the ependymal layer. The presence of GFA‐containing profiles in the ependyma of adult animals is discussed in relation to GFA‐positive structures seen in the human brain during ontogeny or under cer‐tain pathological conditions.