bluuebunny/crossref_metadata_2025_split huggingface dataset:
The abducens nucleus in the carpet shark Cephaloscyllium isabella
Authors: Montgomery John C. , Housley Gary D. 
Published: May 2005

AbstractThis study utilizes retrograde axonal transport of cobaltous‐lysine, and conventional silver and Golgi staining techniques to study the abducens motor nucleus innervating the external rectus muscle of the carpet shark. The nucleus consists of 300–400 motoneurons located immediately ventrolateral to the medial longitudinal fasciculus (MLF), distributed over about 1.25 mm in a rostrocaudal direction at the level of exit of the VI nerve. The axons of the motoneurons form seven or eight discrete ventrally directed fascicles which, having exited from the brainstem, group together to form the abducens (VI) nerve. The motoneurons are on average about 16 μm in diameter, are bipolar, and their dendrites have a transverse orientation. Typically one set of dendrites penetrates the MLF and the other set extends ventrally into the reticular formation.
The intrinsic architectonic and connectional organization of the superior temporal region of the rhesus monkey
Authors: Galaburda Albert M. , Pandya Deepak N. 
Published: May 2005

AbstractThe superior temporal region (STR) in the rhesus monkey includes the circular sulcus (Cis), the supratemporal plane (STP), and the superior temporal gyrus (STG). Rostrally the STR is continuous with the periallocortices of the prepyriform and anterior insular regions; caudally it borders the isocortices of the inferior parietal lobule and the superior temporal sulcus. The STR contains 12 cytoarchitectonic areas: four fields on the Cis, four on the STP, and four on the STG. The sulcal fields (root fields) are adjacent to the insula and resemble it in the possession of a relatively strong layer V; the STP fields (core fields) are characterized by well‐developed layer IV; and the STG fields (belt fields) exhibit strong differentiation of layer III. In each line of fields the more rostral ones show relative prominence of the deeper layers, with increasing prominence of the superficial layers occurring caudad in a stepwise fashion.Analysis of the connectional organization of the fields within the STR suggests an assembly of four rostrocaudal stages, each composed of one field from each line–a root, a core, and a belt field. There is a specific arrangement of connections among the fields of a given stage and between fields in adjacent stages. Projections directed caudally from one field to another field in the adjacent stage arise in layers V and VI and terminate in the superficial layers (mainly layer I). Projections directed to a field in a rostrally adjacent stage arise from layer III neurons and terminate in layers III and IV, usually in columns. There is also a laminar specificity between fields lying within a given stage.
Transient cerebrocerebellar projections in kittens: Postnatal development and topography
Authors: Tolbert Daniel L. , Panneton W. Michael 
Published: May 2005

AbstractOrthograde and retrograde labeling techniques were used to study the ontogenesis of transient cerebrocerebellar projections in kittens. Tritiated amino‐acid or horseradish peroxidase injections were made into the coronal gyms of the primary somatosensory cortex of kittens 1–70 postnatal days old. Orthogradely labeled axons were observed bilaterally in the superior and inferior cerebellar peduncles in kittens between 6 and 49 postnatal days of age. Most cerebrocerebellar axons labeled on the ipsilateral side arise from the pyramidal tract as it courses through the pontine nuclei. These axons descend through the pontine tegmentum as a diffusely organized corticotegmental tract and enter the ipsilateral superior cerebellar peduncle. Fewer cerebrocerebellar axons leave the pyramidal tract caudal to the pontine nuclei and project into the contralateral superior cerebellar peduncle. Cerebrocerebellar projections through the superior cerebellar peduncles terminate pri‐marily in the cerebellar nuclei, where they are localized in the interpositus nuclei and in immediately adjacent areas of the dentate and fastigial nuclei.More caudally, labeled axons exit from the pyramidal tract and take a superficial route around the ventrolateral brainstem into the inferior cerebellar peduncles bilaterally. These projections are more numerous contralaterally and are directed primarily to the internal granule cell layer of the posterolateral folia of the anterior lobe, the posteromedial simplex lobule, and the dorsal paramedian lobule.Horseradish peroxidase injections were made into the cerebellar posterior lobe and deep nuclei and the results from these cases showed that the cerebrocerebellar pathway originates from pyramidal neurons in layer V primarily in the coronal, the precoronal, and the anterior and posterior sigmoid gyri on both sides. In these gyri, many of the HRP‐positive neurons were found in clusters of two to five neurons, aligned in anterior‐posterior strips.The results from all experiments provide evidence about the ontogeny of cerebrocerebellar projections. Projections through the superior cerebellar peduncles generally develop at 6–8 postnatal days of age, whereas projections through the inferior cerebellar peduncles first are seen at 8–10 days postnatally. Cerebrocerebellar projections reach their maximum development in the second postnatal week but sharply decrease in density during the third postnatal week. No cerebrocerebellar projections were observed after the seventh postnatal week of development. Possible functional implications for this transient projection are discussed.
An intracellular HRP study of the rat globus pallidus. II. Fine structural characteristics and synaptic connections of medially located large GP neurons
Authors: Falls W. M. , Park M. R. , Kitai S. T. 
Published: May 2005

AbstractIn order to classify the presynaptic elements contacting the principle class of globus pallidus neurons, electron microscopic examination of serial sections made from a medially located large globus pallidus neuron, labeled with intracellular horseradish peroxidase, was undertaken. In addition, the use of labeled and light microscopically reconstructed material allowed us to quantitatively determine the distribution of each bouton type along the soma and dendrites. Six types of presynaptic terminals contacting the labeled cell have been recognized. Type 1 endings, the most numerous (84%), make symmetrical contacts on all portions of the cell, except spines, contain large pleomorphic, and a few large dense‐core vesicles. Type 2 endings are filled with small spherical‐to‐ellipsoidal synaptic vesicles. They make asymmetrical contacts only with higher‐order dendrites and account for 12% of synaptic contacts onto the labeled neuron. Type 3 endings are large, contain sparsely distributed large pleomorphic vesicles, and make two symmetrical synapses per bouton, one onto a spine head and the other onto the underlying dendritic shaft. They are infrequent (0.2%), being found only in association with dendritic spines. Type 4 endings contain large pleomorphic synaptic vesicles and no dense‐core vesicles. They make symmetrical contacts with the short primary dendrites. Type 5 endings contain a mixture of small clear pleomorphic vesicles and numerous large dense‐core vesicles. They contact only the cell body and the short primary dendrites, making up 20% of somatic synaptic contacts but less than 1% of contacts onto dendrites. Type 6 boutons contain oval and flattened synaptic vesicles and establish symmetrical contacts with higher‐order dendritic branches and the cell body.
Morphology of physiologically identified X‐, Y‐, and W‐type retinal ganglion cells of the cat
Authors: Saito Hide‐Aki 
Published: May 2005

AbstractRetinal ganglion cells of the cat have been classified physiologically into X‐, Y,‐ and W‐cells, on the basis of the receptive field properties, and morphologically into α‐, β‐, and γ‐cells.In order to study directly the correspondence between these classifications, intracellular recordings from the ganglion cells in supervised eye‐cup preparations were made with the aid of microelectrodes filled with Lucifer yellow CH. The cells were stained after their photic responses were studied under mesopic adaptation.X‐cells, showing sustained depolarization (on‐center cells) or hyperpolarization (off‐center cells) in response to a spot of light had medium‐sized round somata and spread bushy dendrites within a narrow retinal area. On the other hand, on‐center and off‐center Y‐cells, showing transient responses to the spot stimulus, had large somata and widely expanded thick dendrites which were sparsely branched. W‐cells which showed weak sustained responses had widely extended thin and winding dendrites, despite a small somal size. These morphological features of Y‐, X‐, and sustained W‐cells correspond well to those of α‐, b̃‐, and δ‐cells (a subtype of γ‐cells), respectively. The hypothesis of “morphology reflecting function” is strongly supported.
Distribution in area 17 of neurons projecting to the pontine nuclei: A quantitative study in the cat with retrograde transport of HRP‐WGA
Authors: Bjaalie Jan G. , Brodal Per 
Published: May 2005

AbstractThe number and distribution of corticopontine neurons within area 17 of the cat were studied quantitatively with the use of retrograde transport of horseradish peroxidase‐wheat germ agglutinin. Eight cats received stereotactic injections in the pontine nuclei; in three of these complete staining of the parts of the pontine nuclei receiving fibers from the visual cortex was achieved. Labeled cells were counted in frontal sections through the hemisphere, spaced at 0.5 mm.The borders of area 17 were determined cyto‐ and myeloarchitectonically and a flat map was produced for each animal. A map of the representation of the visual field in 10° × 10° blocks in the first visual area (Tusa et al., '78, '81) was transferred to our maps of area 17. The density and number of labeled corticopontine cells could then be determined within blocks of the cortex representing 10° × 10° of the visual field.The cell density (number of labeled cells per mm2 cortex) was found in general to be highest in parts of the cortex representing peripheral parts of the visual field. The cell density is low in cortex representing the central visual field, but the lowest density was found in the representation of a paracentral region in the upper visual field. Furthermore, cortical regions representing the lower part of the visual field have a higher cell density than those representing the upper part; in four cases, 68–86% of all labeled cells were found in parts of area 17 representing the visual field below the horizontal meridian.Since there is an enlarged cortical representation of central vision, the much lower cell densities in ‘central’ parts of area 17 than in “peripheral” parts may mean that all parts of the visual field are represented with equal numbers of corticopontine neurons (“linear” representation). This is not the case, however, since the number of labeled cells per 10° × 10° is considerably higher in the cortex representing the central 10° and medial parts of the lower visual field than in the rest of area 17. Assuming that the corticopontine cells in the visual cortex transmit spatially relevant information, we conclude that there is an overrepresentation of central vision and the medial parts of the lower visual field in the corticopontine projection from area 17.
Assessment of possible transneuronal changes in the retina of rats with inherited retinal dystrophy: Cell size, number, synapses, and axonal transport by retinal ganglion cells
Authors: Eisenfeld Amy Jill , Lavail Matthew M. , Lavail Jennifer H. 
Published: May 2005

AbstractIn pigmented RCS rats with inherited retinal dystrophy, most photoreceptor cells disappear between postnatal days 20 and 100. We have examined the time course of the degeneration of photoreceptor nuclei and synapses and determined whether transneuronal changes occur in the inner nuclear layer (INL), inner plexiform layer (IPL), und retinal ganglion cells following loss of photoreceptor cells in these animals.Electron microscopic photomontages of the entire thickness of the IPL of dystrophic (RCS‐p+) and control (RCS‐rdy+ p+) rats 334 to 515 days old were prepared, and synapses were counted and identified as either conventional (amacrine) or ribbon (bipolar) types. Neither the incidence of synapses in the IPL nor the ratio of conventional to ribbon synapses differed in the dystrophic and control retinas.Ganglion cell diameter, perimeter, area, and density were measured from drawings of wholemount preparations of dystrophic and control rats 105 days and older. Diameter, perimeter, area and number of ganglion cells were not significantly different in the two genotypes. Anterograde axonal transport was measured by studying the displacement of labeled material as it traveled along ganglion cell axons and accumulated in the superior colliculus. The normal and dystrophic rats showed no significant difference in (1) the rates of rapidly moving components (approximately 110–180 mm/day) and slowly moving components (1.7–2.5 mm/day) or (2) the amount of radioactive material transported to the superior colliculus.The absence of transneuronal changes in retinal ganglion cells of RCS rats contrasts with results obtained earlier in rd mice (Graftstein et al., '72). Unlike the RCS rat, retinal degeneration in rd mice occurs before the maturation of the retina. We hypothesize that the ganglion cells may be more affected by loss of input early in development, and, therefore, ganglion cells of retinal dystrophic rats are less affected despite little or no synaptic input for several months. Furthermore, any reduction in the electrical activity of retinal ganglion cells that might follow loss of photoreceptor cells does not result in a significantly decreased rate of axonal transport.
Studies on the factors that govern directionality of axonal growth in the embryonic optic nerve and at the chiasm of mice
Authors: Silver Jerry 
Published: May 2005

AbstractWhat are the forces residing at the presumptive chiasm of embryonic mice that control the directionality (i.e., side specificity) of the optic axons? In an attempt to answer this question, the overall trajectories of individual fascicles of early growing axons and the various environments that they encounter along their pathway have been charted from the eye through the nerve and into the base of the diencephalon. Serial sections and reconstructive computer graphic techniques were used for the analysis.The early optic axons (embryonic (E) day 13.5) arrive at the chiasm in a stereotyped topographic arrangement. However, the fiber array at the primitive chiasm is not retinotopically organized nor is it maintained with the same level of spatial precision as it is at the disc. Thus, the annular, inverted retinotopic contingent of “pioneering” axons that exists in the primitive nerve becomes reorganized at the chiasm into a crescent‐shaped configuration, with fascicles from ventrotemporal and ventronasal retina at either side of the crescent and with fascicles from dorsal retina interposed. Because of their gross locations in the crescent, particular clusters of fibers, each largely originating from different retinal sectors, but “contaminated” with fibers from other regions, come in contact with different types of nonneuronal structures at the chiasm. One, a dense, knotlike glial formation that lies along the margin of the diencephalic‐telencephalic junction, directs all adjacent (ventronasal) fibers contralaterally. The other, a discrete pathway of lengthy marginal glial processes, separated by an anastomotic system of large extracellular spaces, guides all nearby fibers from ventrotemporal retina ipsilaterally. The results suggest that fiber topography as well as local environmental factors may play important roles in guiding axons at the chiasm.
Synaptic contacts of somatostatin immunoreactive amacrine cells in goldfish retina
Authors: Marshak David W. , Yamada Tadataka , Stell William K. 
Published: May 2005

AbstractRetinal amacrine cells containing somatostatinlike immunoreactivity (SLI) were labeled by the peroxidase‐antiperoxidase technique and their connections were analyzed by light and electron microscopy. The labeled processes were found in two distinct plexuses—one near the most proximal border of the inner plexiform layer and the other near the most distal border. They received most (89%) of their input from amacrine cells and the remainder from bipolar cells. A majority (56%) of their output synapses go to processes of amacrine cells, a substantial proportion (38%) go to ganglion cell dendrites, and the remainder go to bipolar cell axon terminals. The relative frequencies of each of the types of contacts were nearly identical in the distal and proximal plexuses. The cells containing SLI are different in their morphology and synaptic connections from any goldfish amacrine cells containing conventional neurotransmitters, but one type of amacrine cell containing SLI resembles certain other peptidergic amacrine cells in the goldfish retina.
The somatotopic organization of primary afferent terminals in the superficial laminae of the dorsal horn of the rat spinal cord
Authors: Swett John E. , Woolf Clifford J. 
Published: May 2005

AbstractTransganglionic transport of wheatgerm agglutinin conjugated horseradish peroxidase (WGA‐HRP) was used to reveal the central distribution of terminals of primary afferent fibers from peripheral nerves innervating the hind leg of the rat. In separate experiments the sizes and locations of cutaneous peripheral receptive fields were determined by electrophysiological recording techniques for each of the nerves that had been labeled with WGA‐HRP. By using digital image analysis, the sizes and positions of the peripheral receptive fields were correlated with the areas of superficial dorsal horn occupied by terminals of primary afferents from each of these receptive fields.Data were obtained from the posterior cutaneous nerve of the thigh, lateral sural, sural, saphenous, superficial peroneal, and tibial nerves. The subdivisions of the sciatic nerve, the sural, lateral sural, superficial peroneal, and tibial nerves each projected to a separate and distinct region of the superficial dorsal horn and collectively formed a “U”‐shaped zone of terminal labeling extending from lumbar spinal segments L2 to the caudal portions of L5. The gap in the “U” extended from L2 to the L3‐4 boundary and was occupied by terminals from the saphenous nerve. Collectively, all primary afferents supplying the hindlimb occupied the medial 3/4 of the superficial dorsal horn with terminals from the tibial nerve lying most medially and occupying the largest of all the terminal fields. Afferents from the superficial peroneal lay in a zone between the medially situated tibial zone and the more laterally placed sural zone. Afferents from the posterior cutaneous nerve were located most caudally and laterally. Terminal fields from the posterior cutaneous and saphenous nerves differed from the others in having split representations caused presumably by their proximity to the mid‐axial line of the limb. Comparisons between the peripheral and the central representations of each nerve revealed that 1 mm2 of surface area of the superficial dorsal horn serves approximately 600–900 mm2 of hairy skin and roughly 300 mm2 of glabrous skin. The vast majority of terminal labeling observed in the dorsal horn was found in the marginal layer and substantia gelatinosa, suggesting that small diameter afferents have an orderly somatotopic arrangement in which each portion of the skin surface is innervated by afferent fibers that terminate in preferred localities within the dorsal horn.
Immunocytochemical localization of choline acetyltransferase within the rat neostriatum: A correlated light and electron microscopic study of cholinergic neurons and synapses
Authors: Phelps Patricia E. , Houser Carolyn R. , Vaughn James E. 
Published: May 2005

AbstractMonoclonal antibodies to choline acetyltransferase (ChAT) were used in an immunocytochemical study to characterize putative cholinergic neurons and synaptic junctions in rat caudate‐putamen. Light microscopy (LM) revealed that ChAT‐positive neurons are distributed throughout the striatum. These cells have large oval or multipolar somata, and exhibit three to four primary dendrites that branch and extend long distances. Quantitative analysis of counterstained preparations indicated that ChAT‐positive neurons constitute 1.7% of the total neuronal population. Electron microscopy (EM) of immunoreactive neurons initially studied by LM revealed somata characterized by deeply invaginated nuclei and by abundant amounts of organelle‐rich cytoplasm. Surfaces of ChAT‐positive neurons are frequently smooth, but occasional somatic protrusions and dendritic spines occur. Although infrequently observed, axons of ChAT‐positive neurons branch, receive synapses, and become myelinated. Unlabeled boutons make both symmetrical and asymmetrical synapses with ChAT‐positive somata and proximal dendrites, but are more numerous on distal dendrites. In addition, some unlabeled terminals form asymmetrical synapses with ChAT‐positive somata and dendrites that are distinguished by prominent subsynaptic dense bodies. Light microscopy demonstrated a dense distribution of ChAT‐positive fibers and punctate structures in the striatum, and these structures appear to correlate, respectively, with labeled preterminal axons and presynaptic boutons identified by EM. ChAT‐positive boutons contain pleomorphic vesicles, and make symmetrical synapses primarily with unlabeled dendritic shafts. Furthermore, they establish synaptic contacts with somata, dendrites and axon initial segments of unlabeled neurons that ultrastructurally resemble medium spiny neurons. These observations, together with the results of other investigations, suggest that medium spiny GABAergic projection neurons receive a cholinergic innervation that is probably derived from ChAT‐positive striatal cells. The results of this study also indicate that cholinergic neurons within caudate‐putamen belong to a single population of cells that have large somata and extensive sparsely spined dendrites. Such neurons, in combination with dense concentrations of ChAT‐positive fibers and terminals, are the likely basis for the large amounts of ChAT and acetylcholine detected biochemically within the neostriatum.
The very distal part of the basilar papilla in the chicken: A morphological approach
Authors: Lavigne‐Rebillard Mireille , Cousillas Hugo , Pujol Reḿy 
Published: May 2005

AbstractThe very distal part of the chicken basilar papilla was investigated by light and electron (scanning and transmission) microscopy. The rostral tip of the basilar papilla has a lenticular area with atypical sensory hair cells which are more similar to vestibular than to auditory cells. The structure of the lenticular area appears to be suitable for vestibular function or, more likely, for auditory perception at very low frequencies. Several hypotheses can be proposed to explain this very peculiar portion of the avian cochlea. It is difficult to consider it a continuously growing area since it remains stable in adulthood. A better explanation would be that there is an incomplete ontogenetic or phylogenetic process.