bluuebunny/crossref_metadata_2025_split huggingface dataset:
The organization of forebrain afferents to the paraventricular and supraoptic nuclei of the rat
Authors: Sawchenko P. E. , Swanson L. W. 
Published: January 2005

AbstractAxonal transport techniques were used to define the organization of projections from the forebrain to the paraventricular (PVH) and supraoptic (SO) nuclei of the hypothalamus in the adult rat. First, injections of a retro‐gradely transported fluorescent tracer, true blue, were placed in the region of the PVH, and the distribution of retrogradely labeled cells was charted. Then, the autoradiographic method was used to confirm the results of the retrograde transport experiments, to describe the route taken by inputs to the PVH and SO, and to determine the distribution of each projection within the various subdivisions of the nuclei that have been recognized previously on the basis of cytoarchitectonics, efferent projections, and immunohisto‐chemistry.The results can be summarized as follows. First, direct projections to the PVH arise from all areas of the hypothalamus (except the SO, the medial and lateral mammillary nuclei, and the magnocellular preoptic nucleus), and from the subfornical organ and the bed nucleus of the stria terminalis. Second, every forebrain region projecting directly to the PVH appears to innervate cell groups in parvocellular parts of the nucleus that in turn project to the neurohemal zone of the median eminence, and to autonomic centers in the brainstem and spinal cord. In addition, each input has a unique distribution within the parvocellular division. Third, relatively few regions in the forebrain project directly to magnocellular neurosecretory parts of the PVH, and are thus in a position to influence directly the release of posterior pituitary hormones. These regions (each of which also projects to the parvocellular division) include the dorsomedial nucleus of the hypothalamus, the median preoptic nucleus, the subfornical organ, and the bed nucleus. Therefore, inputs from the hippocampal formation, amygdala, and lateral septum that have been shown to influence the magnocellular neurosecretory system appear to be relayed by way of short projections from other parts of the hypothalamus (including perhaps parvocellular parts of the PVH) and from the bed nucleus. Fourth, most of these cell groups innervate preferentially either oxytocinergic (dorsomedial and bed nuclei) or vasopressinergic (subfornical organ) parts of the magnocellular division of the PVH. Only the projection from the median preoptic nucleus appears to be distributed uniformly over parts of the magnocellular division in which oxytocin‐ and vasopressin‐con‐taining cells are concentrated. And fifth, each region that preferentially innervates either oxytocinergic or vasopressinergic neurons in the PVH also preferentially innervates the same cell type in the SO (which does not contain a distinct parvocellular division). The results indicate that the coordination of neuroendocrine and autonomic responses from the PVH is mediated at least in part by a complex series of neural inputs, each of which innervates more than one functional subdivision within the nucleus.
Birth dates of trigeminal motoneurons and metamorphic reorganization of the jaw myoneural system in frogs
Authors: Alley Keith E. , Barnes Maryann D. 
Published: January 2005

AbstractDrastic alterations in oral behavior characterize metamorphosis of anu ran amphibians. Changes cascade through all components of the jaw appa ratus from bone to muscle to nerve. In this investigation, tritiated thymi dine autoradiography was used to determine the production schedule of the trigeminal motoneurons in the leopard frog, Rana pipiens. The time of origir of these neurons and their subsequent fate are of special interest given the breakdown of the larval jaw muscles and the de novo generation of adul muscle fibers during metamorphosis. Specifically, we wanted toalearr whether trigeminal motoneurons are added, deleted, or reused during meta morphic climax.The entire complement of trigeminal motoneurons was produced over 4‐day span commencing at embryonic stage 13 and terminating at stage 20 Newly formed neurons are added to the primordial trigeminal nucleus in ar orderly pattern. Firstborn neurons settle in the ventrorostral region of the nucleus; cells with progressively later birth dates were added in a postero dorsal direction. No additional trigeminal motoneurons are generated dur ing larval maturation or at metamorphosis, thus indicating that the same population of neurons is present throughout the lifespan of the animal. From these observations we suggest that, during metamorphosis, the trigemina motoneurons that supply the larval muscles switch their allegiance to the newly formed adult jaw muscles. This change of peripheral targets can be viewed as a respecification of the trigeminal motoneurons.
On neuronal homology: A comparison of similar axons in Musca, Sarcophaga, and Drosophila (Diptera: Schizophora)
Authors: King David G. , Valentino Karen L. 
Published: January 2005

AbstractThoracic axons occurring in Musca and Sarcophaga are similar to those previously reported in the giant fiber pathway of Drosophila. Serial section reconstruction of both species has shown that the cervical giant fiber descending from the brain into the thoracic ganglion and the thoracic motor axon innervating the tergotrochanteral muscle follow courses matching those of similar axons in Drosophila. Likewise in both Musca and Sarcophaga a thoracic axon establishes axoaxonal synapses onto dorsal longitudinal muscle motor neurons. This axon is similar in both course and synaptic configuration to the peripherally synapsing interneuron in Drosophila. Although these similarities suggest that the three axon pairs are homologous in all three fly species, several differences are also observed. Thus this system of identified axons may be a useful model for investigating phylogenetic variation in specific neuronal form and connectivity.
A reevaluation of the functional organization and cytoarchitecture of the feline lateral posterior complex, with observations on adjoining cell groups
Authors: Updyke B. V. 
Published: January 2005

AbstractThe organization of the cat's lateral posterior complex was reevaluated and its cytoarchitecture described, Analysis of visual representations within the complex confirmed that the pulvinar, lateral zone (LPl), and interjacent zone (LPi) correspond to separate representations of the visual field and established that the zones exhibit heterogeneous connections as a result of retinotopic interconnections with extrastriate areas which represent varying amounts of the visual field. A common system of visual representation extending through layers with differing anatomical connections was identified within zone LPl. The concept of an “isorepresentation cord” was introduced to describe these variable correspondences between sensory representations and connectional relationships. Isorepresentation cords are conceived as holding in common representation of a common locus on a sensory surface without functioning as a unit with respect to connections. Visual representations wtihin the lateral posterior complex consist of many such cords arranged in orderly array.Zone LPm (medial) was also delineated more accurately on the basis of its connections with the ectosylvian visual area. Analysis of termination patterns which occupy boundary regions adjacent to and between the principal zones further established the existence of a collection of cell groups which form a thin, irregular shell investing the principal zones. The identification of these additional cell groups and the recognition of connectional heterogeneity within the principal zones of the complex made it possible to identify and describe the subtle cytoarchitectural differences which characterize the subdivisions of the lateral posterior complex and their boundaries with adjoining nuclear groups.The present findings are discussed with respect to the functions of the lateral posterior complex in interconnecting cortical visual and visuomotor areas, and with respect to the conceptual issues raised by variable correspondences between sensory representations and connectional relationships within thalamus.
The development of the cervical spinal cord of the mouse embryo. I. A Golgi analysis of ventral root neuron differentiation
Authors: Wentworth Lee E. 
Published: January 2005

AbstractNo previous Golgi studies have described early neuron differentiation in mammals near the time of neural tube closure. By leaving embryos in utero and varying the impregnation times, the cells of the cervical spinal cord of mice of 8–11 days of gestation (E8–E11, where E0 = day vaginal plug observed) were stained and analyzed in the present study. The early stages of ventral root motoneuron differentiation described earlier (Wentworth and Hinds, '78), using serial section electron microscopy, have been confirmed in this study and include preaxonic neuroblasts (stage 1–detached from the ventrical but still attached to the basal lamina), bipolar neuroblasts (stage 2), and unipolar neuroblasts (stage 3). Later stages of differentiation described in this study include young neurons with dendrites: secondary bipolar (stage 4) and multipolar neurons (stage 5). At E8 the neural tube is just closing and consists of undifferentiated ventricular cells. On E9 a few ventral root neuroblasts are differentiating in the cervical spinal cord. The majority of these cells are in the bipolar and unipolar neuroblast stages, although the most advanced cells observed had reached the secondary bipolar neuron stage of differentiation. By E10 a large cluster of ventral root motoneurons is differentiating in the ventrolateral cord. Some cells have reached the bipolar stage, a few cells are becoming multipolar, and a subdivision into dorsolateral and vrntromedial subgroups is beginning. By E11 the medial and lateral subdivisions are more obvious, and the most advanced cells are well‐differentiated multipolar neurons oriented either mediolaterally or dorsoventrally, although cells in the earlier unipolar and secondary bipolar stages are still observed.
The origin of postganglionic and sensory axons in the cervical sympathetic trunk of the cat: A horseradish peroxidase study
Authors: Wong Wai Chow , Leong Seng Kee 
Published: January 2005

AbstractThe composition of the cervical sympathetic trunk (CST) in the cat is still not completely understood. The present study investigates, by the horseradish peroxidase (HRP) method of tracing neuronal connections, the presence of postganglionic and sensory neurons projecting via the CST. Following sympathectomy at the midcervical level and the application of HRP crystals to the cut ends of the CST which had been isolated from the surrounding by a 1.5% solution of agar‐agar, labelled neurons were seen in the superior cervical (SCG), stellate (SG), inferior vagal ganglia (IVG), and spinal ganglia C8–T8. The maximum number of labelled nuerons was 536 in the SCG, 460 in the SG, 180 in the IVG, and 104 in spinal ganglia C8–T8.
Organization within the cranial IX–X complex in ranid frogs: A horseradish peroxidase transport study
Authors: Stuesse Sherry L. , Cruce William L. R. , Powell Katina S. 
Published: January 2005

AbstractCranial nerves IX and X in frogs have been described as originating from a nuclear group referred to as the IX–X complex. We studied the central nervous system components of this complex in Rana pipiens and R. catesbiana by labeling peripheral branches of cranial nerves IX and X and identifying the central nervous system contributions of these branches. Various peripheral nerves (IX and the cardiac, gastric, pulmonary, and laryngeal branches of X) were identified and soaked in horseradish peroxidase (HRP). One to 2 weeks later, the frogs were killed and processed for HRP by the tetramethylbenzidine method. Glossopharyngeal efferents originated from a small ventrolateral cell group found at the level of the IX root exit. Vagal efferents formed a single column of cells in a ventrolateral position from the level of the brainstem exit of the vagus nerve (approximately 2,000 μm above the obex) to 200 μm below the obex (values given are for an 80‐g frog). This cell group was separate from and just caudal to efferent cells of the glossopharyngeal nerve. Within the vagal portion of the column, cells projecting through the gastric branch were found throughout the rostral‐caudal extent of the nucleus. “Cardiac” cells tended to be more rostral than “pulmonary” cells, and both groups of cells were located in the middle of the nucleus. “Laryngeal” cells were located more caudally in the nucleus. This peripheral representation within the vagal nucleus corresponds more closely to the organization found in the mammalian nucleus ambiguus, rather than to the apparent lack of organization found in the mammalian dorsal motor nucleus.Afferents of IX and X entered slightly rostral to the ventral roots of their respective nerves and descended in two tracts. The majority entered the tractus solitarius and descended in a medial position to cervical spinal cord. A portion of the afferents from the vagus nerve crossed the midline in the lower myelencephalon just dorsal to the central canal and ascended a short distance on the contralateral side. Within the solitary tract, vagal afferents were located in a ventrolateral position as they descended to below the obex. Glossopharyngeal afferents filled the remainder of the tract. A smaller portion of afferents from both IX and X did not enter the solitary tract but descended in the spinal tract of V and the dorsolateral funiculus of the spinal cord (Lissauer's tract) to thoracic levels. Afferents of IX also formed a rostral bundle which extended in the solitary tract to the caudal metencephalon.
Morphometry of spine‐free nonpyramidal neurons in rabbit auditory cortex
Authors: McMullen Nathaniel T. , Glaser Edmund M. , Tagamets Malle 
Published: January 2005

AbstractA study of the morphometry and laminar distribution of spine‐free nonpyramidal neurons in electrophysiologically verified primary auditory cortex was carried out in adult rabbits. By using image‐combining computer microscopy, the locations of all impregnated neurons in 300‐μm Golgi‐Cox Nissl sections through the auditory cortex were determined. Spine‐free non‐pyramidal neurons constitute nearly 72% of the nonpyramidal neurons present. They are distributed in a band extending from 450 to 750 μm beneath the pial surface corresponding to laminae III and IV. A combination of dendritic stick, Fourier, and statistical analyses revealed a highly significant spatial orientation of their dendrite systems along a vertical axis parallel to the apical dendrites of pyramidal neurons. A significant tangential orientation of dendrites along a dorsal‐ventral axis was also found. A radial analysis of the dendrite systems revealed that the pronounced vertical orientation of spine‐free nonpyramidal neurons is due to (1) directed dendritic growth along the vertical axis, (2) decreased branching and rapid termination of tangentially oriented dendrites, and (3) increased branching of vertically growing dendrites. The radial analysis also revealed that the longest branches are those directed toward the white matter.
A study of axonal diameters and areas in lumbosacral roots and nerves in the rat
Authors: Suh Young Suk , Chung Kyungsoon , Coggeshall Richard E. 
Published: January 2005

AbstractThere has been debate as to whether there is a size difference between central and peripheral processes of dorsal root ganglion cells. In the present study, the mean areas of myelinated and unmyelinated fibers are measured as 27.8 μm2 and 0.55 μm2, respectively, in peripheral nerves and 13.72 μm2 and 0.14 μm2 in dorsal roots. Thus myelinated central processes of dorsal root ganglion cells have mean areas 50% less than the mean areas of the myelinated sensory axons in the same peripheral nerves, and the mean diameters of the central myelinated axons are 30% less than the peripheral myelinated axons. The mean areas of the unmyelinated sensory axons in the dorsal roots are 25% of the mean areas of the unmyelinated sensory axons in the same peripheral nerves. Thus the mean diameters of the central unmyelinated axons are 50% of the mean diameters of the unmyelinated sensory axons in the same peripheral nerve. These data indicate that both myelinated and unmyelinated central processes of dorsal root ganglion cells are smaller than the peripheral processes of these same cells for lumbosacral segments in the rat. It is shown that axonal tapering is not responsible for these striking differences. Finally, documentation of differences in myelinated fiber histograms from dorsal roots of different segments in the rat is provided.
Morphology of inspiratory neurons located in the ventrolateral nucleus of the tractus solitarius of the cat
Authors: Berger A. J. , Averill D. B. , Cameron W. E. 
Published: January 2005

AbstractThe morphology of 11 dorsal respiratory group (DRG) inspiratory neurons located in the ventrolateral nucleus of the solitary tract (vl‐NTS) was studied using the technique of intracellular labeling with the enzyme horseradish peroxidase (HRP). Six of these cells were cut in the transverse plane and had a mean somal diameter of 30.4 m̈m, while five others sectioned in the horizontal plane had a mean of 38.2 m̈m. These neurons produced an average of 6.2 primary dendrites (range: 4–10), many of which projected rostrally or caudally up to 1.0 mm from the cell bodies. These dendrites were oriented along the longitudinal axis; they ran parallel and ventral to the tractus solitarius. In general, all dendrites possessed numerous spines and appendages. Many axons could be traced for considerable distances within the medulla (in one instance, up to 8 mm). These axons were last discerned in the contralateral ventral medulla rostral to the level of their cell bodies. The axons of three neurons bifurcated in the ipsilateral medulla; one branch remained ipsilateral and projected caudally, while the other crossed the midline. A small number of counterstained cells of size similar to or larger than the HRP‐stained neurons formed a column that constituted the vl‐NTS. Based upon our observations of stained and counterstained cells, we conclude that the inspiratory neurons of the vl‐NTS are few in number and represent a morphologically homogeneous population. The primary orientation of the dendritic arbors of vl‐NTS inspiratory neurons appears to optimize the surface area available to receive synaptic contacts from sensory afferents emerging from the tractus solitarius.
Reconstructions of corticogeniculate axons in the cat
Authors: Robson J. A. 
Published: January 2005

AbstractThe terminal arbors of corticofugal axons to the dorsal lateral geniculate nucleus in the cat were filled with horseradish peroxidase and then partially reconstructed through serial sections. The results demonstrate that these arbors are far more complex than was suspected from previous studies of axon segments in individual sections. These axons branch profusely and spread widely within the nucleus. Within laminae A and A1 the terminal arbor of a single axon can be more than 800 μm wide compared with retinogeniculate axons whose terminal arbors range in width from 100 to 410 μm (Sur and Sherman, ′82).
Geniculocortical projection to layer I of area 17 in kittens: Orthograde and retrograde HRP studies
Authors: Kato Nobuo , Kawaguchi Saburo , Miyata Hirofumi 
Published: January 2005

AbstractUsing the orthograde and retrograde HRP methods, the distribution of geniculocortical (G‐C) afferent terminals in area 17 was examined in kittens and an adult cat. Following HRP injection in the entire dorsal lateral geniculate nucleus (LGNd), afferent terminals were labeled in layer I and deeper layers. The terminals in layer I in young kittens (less than 2 weeks old) were densely distributed throughout layer I, whereas in old kittens (over 1 month old) they were sparsely distributed in the outer half of layer I. When the HRP injection site was confined to the A laminae (lamina A and lamina A1), a few HRP‐labeled terminals in layer I were seen in young kittens but not in older kittens or an adult cat. Following HRP injection in layer I of area 17 in young kittens, relatively large neurons were labeled retrogradely. The labeled neurons were located chiefly in the C complex and partly in the A laminae.The present experiments revealed that the G‐C afferents to layer I of area 17 in young kittens originate from relatively large neurons which are located chiefly in the C complex and partly in the A laminae and that these afferents give dense terminals covering the entire layer I. These findings contrast with those obtained in adult cats, in which the G‐C afferents to layer I originate exclusively from small neurons in the C complex and give sparse terminals to the outer half of layer I.
Asymmetry of the olfactory system in the brain of the winter flounder, Pseudopleuronectes americanus
Authors: Rao P. D. Prasada , Finger Thomas E. 
Published: January 2005

AbstractAdult flatfishes exhibit grossly asymmetric external morphology. Even the olfactory apparatus is asymmetric, being larger on the upward‐facing side. We undertook the present study on the winter flounder, Pseudopleuronectes americanus, to examine whether the asymmetry of the peripheral olfactory system is maintained in its central organization. In winter flounder, the right olfactory organ, nerve, and bulb are larger than the contralateral counterparts. In addition, the right telencephalon is about 8% larger than the left. Horseradish peroxidase (HRP) and degeneration techniques were used to trace the central connections of the olfactory bulbs.Neurons afferent to the olfactory bulb occur bilaterally in the telencephalon and mesencephalic tegmentum. Afferent neurons are also present at the junction between the posterodorsal bulb and telencephalon, in the basal preoptic region, nucleus of the posterior tuber, locus coeruleus, raphe nucleus, and the contralateral bulb.Each olfactory bulb projects bilaterally to several restricted areas of the telencephalon, the posterodorsal neurons of the nucleus preopticus and the tuberal region, with ipsilateral connections being heavier in all areas. Corresponding to the differences in the peripheral olfactory apparatus, the central olfactory projections were also asymmetric. The right olfactory bulb projects to 2.6% of the ipsilateral telencephalon and 1.99% of the contralateral telencephalon. The left bulb projects to 1.8% of the ipsilateral and 0.6% of the contralateral telencephalic hemisphere. Thus the left telencephalon receives roughly equal olfactory input from the two sides, while the right telencephalon receives vastly more input from the right olfactory system. The asymmetry in the projections of the right and left bulbs may be due to differential postmetamorphic growth of the olfactory system on the two sides.