bluuebunny/crossref_metadata_2025_split huggingface dataset:
The medial forebrain bundle of the rat. II. An autoradiographic study of the topography of the major descending and ascending components
Authors: Veening Jan G. , Swanson Larry W. , Cowan W. Maxwell , Nieuwenhuys Rudolf , Geeraedts Leo M. G. 
Published: January 2005

AbstractThe medial forebrain bundle (MFB) is a complex fiber system that courses through and partly arises and partly terminates within the lateral preoptic and lateral hypothalamic areas. It consists mainly of thin fibers and may be comprised of as many as 50 descending and ascending components of varying lengths and of different origins and/or destinations (Nieuwenhuys et al., 1982). With the aid of an an atlas of the MFB and the surrounding brain areas in the rat presented in the preceding paper (Nieuwenhuys et al.,1982), the position and topographic relationships of some 21 components of the bundle have been analyzed in detail, in brains that had been prepared for autoradiography following injections of tritiated amino acids into a number of structures that are known to contribute fibers to the MFB. From this analysis it is clear that most of the labeled components occupy specific and rather constant positions within the MFB. For example, the ascending components are largely confined to the dorsal half of the bundle; those arising from the medial preoptic area and the various hypothalamic nuclei are distributed rather diffusely over much of the MFB; and the descending components that arise from the olfactory tubercle and the magnocellular preoptic nucleus are confined to restricted parts of the bundle. These findings indicate that the neurons which occupy different parts of the lateral hypothalamic area probably receive distinctive inputs, and to a first approximation these are likely to be determined principally by their position within the MFB.
The ultrastructure of the subnucleus gelatinosus of the nucleus of the tractus solitarius in the cat
Authors: Leslie R. A. , Gwyn D. G. , Hopkins D. A. 
Published: January 2005

AbstractThe dorsomedial region of the nucleus of the tractus solitarius termed the subnucleus gelatinosus (SNG) was studied at the light and electron microscopic level in the cat. In cresyl violet and luxol fast blue stained sections the SNG contained small neuronal somata that were scattered throughout a pale‐staining neuropil containing few myelinated fibers. These neurons were difficult to impregnate with Golgi staining techniques, but in successful impregnations the somata were observed to be 10–19 μm in diameter and bore few sparsely branching primary dendrites. Spines were present on the dendrites of some neurons and were more numerous on distal portions of the dendritic tree.Ultrastructural examination of the SNG revealed that the neuronal complement consisted of round, oval, or spindle shaped neurons with little or no organized Nissl substance. Rare myelin‐like ensheathments of neuronal perikarya were also observed. Bundles of fine unmyelinated axons that coursed mainly longitudinally were a prominent feature of the area. The most common type of axon terminal observed contained mainly round clear vesicles, approximately 31 nm in diameter, and made asymmetrical synaptic contact with a dendritic profile. Pleomorphic vesicle‐containing terminals involved in symmetrical synaptic contact were also commonly seen. Axodendritic and axosomatic synapses were associated with terminals containing either round clear vesicles or pleomorphic vesicles. Less commonly, dendrodendritic and dendrosomatic synapses were seen, the presynaptic elements of which contained pleomorphic vesicles.Following removal of a nodose ganglion, degenerating terminals of vagal afferent fibers were observed throughout the neuropil. Such terminals contained round, clear vesicles with an occasional large, dense‐cored vesicle, and made axodendritic and axosomatic synaptic contacts.
Retinotectal map formation in dually innervated tecta: A regeneration study in Xenopus with one compound eye following bilateral optic nerve section
Authors: Straznicky Charles , Tay David 
Published: January 2005

AbstractRetinotectal map formation was studied during regeneration in young adult Xenopus. Right compound double‐temporal eyes (TT) were formed in tailbud stage embryos by the fusion of two temporal halves of the eye blastema in the same orbit. In other animals right compound double‐nasal eyes (NN) were prepared. In both combinations the left eye was kept intact. After metamorphosis the right and left optic nerves were sectioned to induce optic fiber regeneration from each eye to both tecta. The patterns of retinotectal projections from the compound and normal eyes were studied from 37 to 364 days after optic nerve section, using electrophysiological recording of the visuotectal projections and 3H‐proline autoradiographic assay from one of the two eyes.The left normal eyes projected in a retinotopic fashion, across the entire extent of the right and left dually innervated tecta. In contrast, the right compound eye projections were confined to the rostrolateral or to the caudomedial part of the right and left tecta in TT and NN animals, respectively. These tectal areas corresponded to the termination of temporal and nasal hemiretinal fibers of the normal eye. Discontinuous, interdigitating projection patterns from the right and left eyes were found in parts of the tecta where the compound and the normal eye projections overlapped.These results indicate that the normal optic fiber projections caused the originally expanded compound eye projections to be restricted to the corresponding part of the dually innervated tecta. It is suggested that the orderliness and the extent of the retinotectal map are established by the competition and interaction of optic fibers based on stable positional programming of the retinal ganglion cells.
The organization of subcortical projections of the hamster's visual cortex
Authors: Lent Roberto 
Published: January 2005

AbstractThe subcortical projections of the hamster's visual cortex were determined by use of injections of tritiated proline and heat lesions placed in different cortical loci. The brains were processed for autoradiography and silver impregnation of degenerating axons. Striate cortex was shown to project ipsilaterally to the dorsocaudal region of the caudate nucleus, a dorsolateral area within the thalamic reticular nucleus (RT), a laterodorsal region of the nucleus lateralis anterior (LA), the rostral half of nucleus lateralis posterior (LP), the whole territory of the dorsal (dLGN) and ventral (vLGN) geniculate nuclei, the anterior (PA) and posterior (PP) pretectal nuclei, the superior colliculus (SC), and the precerebellar pontine nuclei. In addition, the medial visual area (18b) was shown to project to a medial band of LA and part of the caudal half of LP, while the adjoining parietal cortex was seen to terminate in a lateral part of the caudate, a ventral band of LA, and the ventral half of rostral LP. Segregation of different cortical inputs was clear in LA, LP, caudate, and pons. The projections to dLGN, vLGN, SC, LP, and PA were retinotopically organized. Clear evidence of some topography was found within RT, PP, and the pons, although a consisten map could not be derived from the data.
Reevaluation of projections from the mesencephalic trigeminal nucleus to the medulla and spinal cord: New projections. A combined retrograde and anterograde horseradish peroxidase study
Authors: Ruggiero David A. , Ross Christopher A. , Kumada Mamoru , Reis Donald J. 
Published: January 2005

AbstractMicroinjection of horseradish peroxidase (HRP) into the medullary parvocellular reticular formation (NPvc) resulted in retrograde labeling of neurons throughout the mesencephalic trigeminal nucleus (Mes V). Labeled cells were large and ovoid and were distributed primarily in the expanded pontine part of the nucleus. However, none of the small neurons in Mes V were labeled. Injections of HRP made into adjacent brainstem structures including the nucleus gigantocellularis, ventrolateral reticular formation, vestibular complex, and the spinal trigeminal nucleus failed to label neurons in Mes V. Injections made into the medullary raphe and into regions reported to receive inputs from Mes V–spinal cord, nucleus tractus solitarius, hypoglossal nucleus, and facial nucleus–were also not followed by transport to Mes V. Anterograde axonal transport of HRP from the region of reticular formation innervated by Mes V also labeled axons projecting to Mes V and to visceral and somatic sensorimotor nuclei in the lower brainstem. Recent reports of afferents from the amygdala to Mes V suggest that reflexes involving the mesencephlic trigeminal nucleus might be modulated by signals from limbic and autonomic as well as somatic centers in the brain.
Selective uptake of lucifer yellow by retinal cells
Authors: Sarthy P. Vijay , Johnson Steve M. , Detwiler Peter B. 
Published: January 2005

AbstractWhen turtle retinae were incubated with the fluorescent dye, lucifer yellow, in the absence of Ca2+, the dye was selectively accumulated by cell bodies located in the inner nuclear layer (INL). The morphological features of the labeled cells suggested that they were bipolar cells. Other fluorescent dyes, Procion yellow and Primulin, were also taken up by somata in the INL, in the absence of external Ca2+, although the identity of the labeled cells was uncertain. As with turtle retina, lucifer yellow was accumulated predominantly by cell bodies in the INL of goldfish, frog, and rat retinae. Lucifer yellow uptake appeared to be independent of synaptic activity since dark‐adaptation or aspartate treatment of retinae did not alter the dye uptake. Further, retinae from dystrophic (RCS) rats showed uptake similar to that seen in normal rat retinae. After uptake, most of the dye was found intracellularly as patches or vacuoles in the somata of the labeled cells. Dye uptake was not inhibited by removal of Na+ from the incubation medium. Further, prior treatment with metabolic inhibitors, cyanide and iodoacetate, or cytochalasin B, did not block the dye uptake.
An analysis of the number and composition of the synaptic populations formed by photoreceptors of the fly
Authors: Nicol D. , Meinertzhagen I. A. 
Published: January 2005

AbstractThe photoreceptor terminals of newly eclosed female flies, Musca domestica, have been sampled in the first optic neuropile (or lamina) in one of two ways: first, in large number (n = 760) from single sections and second, from serial electron micrographs of the six terminals within each of three cartridges. Both sampling methods concur in assessing the number of synapses established with the two principal monopolar relay interneurons, L1 and L2, within each cartridge. Each receptor is calculated to be presynaptic at about 200 ± 40 (2 SE) synapses. This value considerably exceeds previous estimates, primarily because we took careful account of the appearance of synapses in different section planes. The number of these synapses correlates highly with the area of receptor terminal presynaptic membrane, so that each synapse is allotted, on average, about 1.6 μm2. The synapses are evenly graded in their distribution with an unexplained 23% decrease in both membrane perimeter and synapse number halfway along their receptor terminal's length. The numbers of synapses per receptor did not vary systematically within two horizontal (3 × 20 cartridge) strips of frontal, equatorial lamina sampled. Individual synapses are elongate tetrads (Burkhardt and Braitenberg, ′76) with two pairs of postsynaptic elements. The first pair is invariably contributed by the interneurons L1 and L2 (one each). The second pair comes either from the α processes of an amacrine cell or from a glial cell. In the distal lamina, however, L3 contributes one of the two postsynaptic processes, the second being αor glial. The overall ratio of postsynaptic involvement at distal synapses (α:glial:L3) is 55%, 20%, and 12% respectively, the remainder being unidentified.
Cells of origin of the spinoreticular tract in the monkey
Authors: Kevetter Golda A. , Haber Lawrence H. , Yezierski Robert P. , Chung Jin Mo , Martin Richard F. , Willis William D. 
Published: January 2005

AbstractThe distribution of the cells of origin of the primate spinoreticular tract was determined following injections of horseradish peroxidase (HRP) into the pontomedullary reticular formation in Macaca fascicularis. Five animals received large bilateral injections which included the raphe nuclei and seven monkeys received smaller, unilateral injections. Sections sampled were from upper cervical levels, the cervical enlargement, upper and lower thoracic levels, and lumbosacral levels. The laminar distribution of spinoreticular cells in all spinal cord levels was comparable. More than half of the labeled cells were located ventromedially, in laminae VII and VIII. HRP‐labeled cells were also found in the dorsal horn, primarily in the lateral reticulated part of lamina V. Some cells were also found in laminae I and X. Spinoreticular cells in the lumbosacral spinal cord mainly projected to the contralateral brainstem. In the cervical enlargement, however, a bilateral distribution of cells was observed following unilateral injections of HRP. Most spinoreticular cells were multipolar neurons with extensive dendritic ramifications. The distribution of spinoreticular cells is similar to the distribution of spinal cord neurons that project to the medial thalamus, but different from that of spinal neurons projecting to the ventrobasal complex. The anatomical organization of the spinoreticular tract is consistent with a role for this pathway in nociception.
Connections between the frontal eye field and pretectum in the monkey: An anterograde/retrograde study using HRP GEL and TMB neurohistochemistry
Authors: Leichnetz George R. 
Published: January 2005

AbstractHorseradish peroxidase (HRP) gel implants in the frontal eye field (FEF) of macaque monkeys, processed with tetramethylbenzidine (TMB) neurohistochemistry and studied with darkfield microscopy, demonstrated bidirectional HRP labeling of the afferents and efferents of this cortical area. It was evident that among the entire scope of its inputs, the FEF received a prominent afferent projection from the nucleus of the optic tract (NOT, nucleus limitans) and the suprageniculate nucleus, and projected to a medial subdivision of NOT, sublentiform nucleus, nucleus of the pretectal area, nucleus of the posterior commissure, and the rostral periaqueductal gray. The directafferent projections to FEF from NOT could provide a route for visual inputto reach FEF via the pretectum without first going to the visual cortex. The efferents probably represent the pathway through which FEF influences pupillary dynamics known to accompany, or occur independently of, eye movements.
The corticopontine system in the rat. II. The projection pattern
Authors: Wiesendanger R. , Wiesendanger M. 
Published: January 2005

AbstractThe projection from various cortical areas to the pontine nuclei (PN) of rats was investigated with anterograde tracing methods. As a general topological rule, a medial to lateral succession of the PN projection fields from the motor, somatosensory, and visual cortices was observed. Apart from the main “private” projections, each cortical area was found to send fibers also to disjunctive “extra‐projection” territories which receive convergent inputs from two or more cortical areas. The sensorimotor and visual cortices provide the bulk of corticofugal fibers, but contributions from the following association areas were noted: frontal cortex, (dependent of the thalamic mediodorsal nucleus), rhinal sulcus region, and cingulate cortex.
Laminar organization of mitral and tufted cells in the main olfactory bulb of the adult hamster
Authors: Macrides Foteos , Schneider Stephen P. 
Published: January 2005

AbstractMorphometric analyses of Golgi‐impregnated mitral and tufted cells in the main olfactory bulb of the hamster indicate that these second‐order neurons cannot be considered a homogeneous population. They are comprised of several categories based on differences in the sizes and spatial organizations of their dendritic fields and in their likely patterns of lateral and recurrent interactions with granule cells and/or periglomerular cells. External tufted cells have their somata in the periglomerular region or at the superficial border of the external plexiform layer (EPL) and can be subdivided into three morphological categories. Many external tufted cells lack secondary dendrites, i.e., all of their dendrites arborize within glomeruli. Most of these neurons are not in positions where they could receive synaptic contacts from granule cells and thus are likely to receive interneuronal input predominantly from periglomerular cells. Another category of external tufted cells is characterized by secondary dendrites which are highly branched and form dense but spatially restricted fields in the EPL. In contrast, external tufted cells in the third category have sparsely branched secondary dendrites which extend tangentially in the EPL and tend to be asymmetrically distributed with respect to the soma. Most of the deeperlying tufted cells, and the mitral cells, have sparsely branched secondary dendrites whose lengths and laminar distributions within the EPL are correlated with the depths of their parent somata. Internal tufted cells, which have their somata in the deep one‐third of the EPL, and mitral cells exhibit the largest secondary dendritic fields. These fields extend tangentially within the EPL in relatively symmetric radial patterns from their parent somata and envelop substantial proportions of the EPL. Middle tufted cells have their somata in the superficial two‐thirds of the EPL and exhibit secondary dendritic morphologies which are intermediate between those of internal and external tufted cells. These differences in the size and spatial organization of secondary dendritic fields are likely to be associated with differences in the amount and spatial distribution of lateral and recurrent inhibition mediated through synaptic contacts with granule cells. External tufted cells which lack secondary dendrites have large glomerular arbors that are comparable in size to those of mitral and internal tufted cells, whereas external tufted cells with secondary dendrites and middle tufted cells tend to have relatively small glomerular arbors. The morphological differences among mitral and tufted cells and the likely differences in their synaptic interactions within the olfactory bulb, together with recent evidence that these neurons differ in their pharmacology and in their patterns of interconnections with more central regions of the forebrain, suggest that the mitral and tufted cells and the central olfactory circuits may be organized as functionally defined parallel pathways.
Glutamate‐induced cellular injury in isolated chick embryo retina: Müller cell localization of initial effects
Authors: Casper Daniel S. , Trelstad Robert L. , Reif‐Lehrer Liane 
Published: January 2005

AbstractThe neurotoxic and gliotoxic effects of glutamate and several glutamate analogues were studied in isolated chick embryo retinas. To facilitate examination of initial pathological events, a short‐term incubation system was developed and used for light microscopic and autoradiographic investigation. Low‐dose, short‐term glutamate treatment of 12‐day retinas resulted in a glial‐specific lesion in the Müller cells, characterized by extensive cellular edema; at higher concentrations and/or longer treatment times, neurotoxic as well as gliotoxic effects were seen. The early glial damage was identical in appearance to that seen after incubation with DL‐α‐aminoadipate and other reported gliotoxins. No evidence of a similar glialspecific action was seen after administration of kainic acid, although extensive neuronal degeneration did result.Incubation of retinas with tritiated glutamate (3H‐glu) revealed a selective uptake of the label by Müller cells. Autoradiographic grains were localized over Müller foot processes at the inner limiting membrane, and by 30 minutes labeled the entire glial system. Prior treatment with neurotoxic levels of glutamate did not alter the autoradiographic localization to glial cells.Possible glial‐neuronal interactions and their effect on cytotoxic patterns are discussed.
Dendritic tree structure and dendritic hypertrophy during growth of the crucian carp eye
Authors: Kock Jan‐Henrik 
Published: January 2005

AbstractThe areas of the ganglion cell dendritic trees were determined in Golgistained, flatmounted retinas of crucian carp ranging in age from one summer to 7 years. The dendritic trees of small ganglion cells (S‐GC), forming the majority of retinal ganglion cells, add new branches as the retina grows. The increase in dendritic tree area exactly compensates for the decrease in ganglion cell density during growth of the eye so that the number of dendritic trees covering a particular point remains constant. While the retinal diameter increases by a factor of 2.5, the mean diameter of the S‐GC dendritic fields increases by a factor of 1.9 and the visual angle covered by one S‐GC dendritic tree decreases from 1.6° to 1.2°.The number of branching points of the S‐GC dendrites is significantly higher in the ventral retina than in the dorsal. In general the dendrites of the S‐GCs tend to grow towards the retinal margin. Dendritic orientation patterns of large (LGC) and large displaced (LDGC) ganglion cells closely resemble those of the amacrines, being oriented parallel to the retinal margin over a wide peripheral region, while the SGCs rapidly lose their tangential orientation. The dendrites of the SGCs are restricted mainly to the proximal sublayer of the inner plexiform layer, suggesting they are ON‐cells, while LGC, LDGC, and amacrine cell dendrites are distributed in depth bimodally.As determined from Golgi‐stained sections the crucian carp has the same basic IPL organization as the carp and cat.
The reticulocerebellar projection to the pyramis and copula pyramidis in the rat: An experimental study using retrograde transport of horseradish peroxidase
Authors: Eisenman Leonard M. 
Published: January 2005

AbstractThe organization of the lateral reticulocerebellar projection to the pyramis and copula pyramidis in the rat was studied with the use of microinjections of horseradish peroxidase (HRP). These injections were mae in different mediolateral positoins along the width of this lobule. The objective was to determine whether reticulocerebellar parasagittal zones (Chan‐Palay et al., 1977) receive differential inputs from the lateral reticular nucleus (LRN). This material has previously been used to analyze the olivo and pontocerebellar projection to this same cortical region of the rat cerebellum (Eisenman, 1981a,b). The results do not support a clear‐cut topographic organization in this projection system to the pyramis and copula pyramidis in the rat. There is some suggestion, however, of a difference in emphasis in the region of the LRN projecting to different mediolateral positions in this lobule. Injections in medial and lateral parts of this lobule result in the labeling of cells in the subtrigeminal and ventral parts of the parvicellular and magnocellular divisions. Injections in intermediate parts of this lobule result in the labeling of cells primarily in the subtrigeminal division. However, cells in each of the divisons (primarly the subtrigeminal and parvicellular) are labeled in each experiment. These results are discussed with reference to electrophysiological and other anatomical studies of the topography of the reticulocerebellar projection in the cat.