bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dendritic plasticity in mouse barrel cortex following postnatal vibrissa follicle damage
Authors: Harris Roger M. , Woolsey Thomas A. 
Published: January 2005

AbstractNeonatal damage to a row of mystacial vibrissae in the mouse causes cytoarchitectonic alterations in the contralateral SmI barrel cortex. The region for the appropriate row of barrels develops as a smaller homogeneous zone while barrels in adjacent rows are expanded. To investigate the effects of this pehnomenon on the morphology of individual neurons, adult mice in which Row‐C vibrissae (the middle row) had been cauterized on days 1–5 following birth were processed by the Golgi‐Cox method. All neurons in layer IV of the Row‐C zones, of the Row‐C barrels of a control hemisphere, and some neurons in the adjacent enlarged Row‐B barrels were measured with a computer‐assisted microscope. Their location with respect to cytoarchitectonic boundaries was determined from a Nissl counterstain. Data from 239 cells are presented. For each cell, measures of dendritic length and branching were obtained. The orientation of the dendritic trees with respect to the barrel sides was also measured.The measures of dendritic lenghts and branching did not show any differences between control and experimental animals or between animals damaged on different days. Measures of orientation did show changes related to the age at the time of damage. In animals damaged on postnatal day (PND)‐3 or earlier, many cells in the Row‐C zone were observed with dendrites orienting toward the adjacent Rows‐B or ‐D. “Putative” Row‐C cells in the expanded parts of Rows‐B and ‐D were strongly oriented toward barrels in those rows. These results suggest that dendritic length and branching may be determined intrinsically but that the orientation of the dendritic trees appears to be strongly influenced by the pattern of extrinsic afferent inputs from the thalamus. In the case of the whisker‐damaged animals, the orientation of the Row‐C neuron dendritic trees toward the “functional” thalamocortical inputs in Rows‐B and ‐D contributes strongly to the resultant cytoarchitectonic changes. The implications of these results for normal developmental processes and their relationship to functional studies of the cortex are considered.
Immunocytochemical localization of catecholamine synthesizing enzymes and neuropeptides in area postrema and medial nucleus tractus solitarius of rat brain
Authors: Armstrong D. M. , Pickel V. M. , Joh T. H. , Reis D. J. , Miller R. J. 
Published: January 2005

AbstractThe catecholaminergic and peptidergic neurons in the area postrema and adjacent portion of the medial nucleus tractus solitarii (mNTS) were characterized by the immunocytochemical localization of the catecholamine synthesizing enzymes tyrosine hydroxylase (TH), dopamine‐beta‐hydroxylase (DBH) and phenylethanolamine‐N‐methyltransferase (PNMT) and two neuropeptides, substance P and (Leu5)‐enkephalin. The catecholamine synthesizing enzymes TH and DBH, found jointly only in noradrenergic and adrenergic neurons, were localized in cells having a similar morphology and topographical distribution. These cells were located throughout the rostrocaudal and dorsoventral extent of the area postrema, as well as in neurons within the mNTS. The processes showing TH and DBH immunoreactivity appear to form reciprocal connections between the area postrema and mNTS. Phenylethanolamine‐N‐methyltransferase, the enzymatic marker found only in adrenergic neurons, was detected immunocytochemically in terminals distributed throughout the area postrema and in neuronal perikarya and varicosities within the adjacent mNTS. Like the catecholamine synthesizing enzymes TH and DBH, enkephalin‐like immunoreactivity was localized to perikarya, proximal processes and varicose axon terminals within the area postrema and the adjacent mNTS. However, in contrast to the widespread distribution of the enzymes, the enkephalin‐like immunoreactivity was localized predominantly along the dorsal and ventrolateral margins of the area postrema. The distribution of substance P immunoreactivity, which was detected only in varicose processes, paralleled the distribution of enkephalin‐like immunoreactivity, being predominantly located along the dorsal and ventrolateral margins of the area postrema. Within the mNTS adjacent to the area postrema, substance P immunoreactivity was localized to neuronal perikarya, proximal processes and varicose axon terminals. Based upon the presence of appropriate biosynthetic enzyme markers and neuropeptide localization, these findings suggest that neurons within the area postrema contain noradrenalin and enkephalin and that the afferent axons contain substance P, adrenalin and, probably, noradrenalin.
Neurogenesis of the sexually dimorphic nucleus of the preoptic area in the rat
Authors: Jacobson Carol D. , Gorski Roger A. 
Published: January 2005

AbstractThe sexually dimorphic nucleus of the preoptic area (SDN‐POA) of Sprague‐Dawley rats is larger in volume in the male and hormone‐dependent early in postnatal life. In the present study, we compared for each sex the time course of neuroblast proliferation which forms SDN‐POA or adjacent medial preoptic area (MPOA) neurons. Additionally, we investigated whether there is a temporal gradient of production of neurons in relation to their final position within the SDN‐POA. On day 14, 15, 16, 17, or 18 postfertilization (pf) pregnant rats were given a single injection of 3H‐thymidine (*thy). At 30 postnatal days of age the pups were sacrificed and brain sections were prepared and processed for autoradiography. Three sections of the SDN‐POA and an adjacent area just lateral to it in the MPOA wer also analyzed. In the MPOA and the SDN‐POA the percentage (%) of labeled neurons decreases as the day of injection of *thy approaches the end of gestation, but the time period in which neuroblast divisions occurred is markedly different for the SDN‐POA as compared to that for the MPOA. DNA synthesis occurs as late as day 18pf for neurons which form the SDN‐POA but ceases on day 16pf for those destined for the MPOA. There is a sex difference in neuronal production on both day 14 and 17pf for neurons destined for the SDN‐POA. After injection on day 14pf the % labeled neurons is larger in the female than in the male but after injection on day 17pf this is reversed. There are also significant sex differences as well as a temporal gradient associated with the % labeled neurons in the SDN‐POA in relation to their final anterior‐posterior position. In addition, this study confirms our previous results which justify labeling the SDN‐POA a nucleus, since neuronal density in this region in the male and female is significantly greater than that in the surrounding MPOA. These data illustrate that the specific neurons which comprise the SDN‐POA in both the male and female are being produced as late as day 18pf, whereas neurons located in the MPOA but not in the SDN‐POA have all been born by day 16pf. Neuroblast division which produces the neurons of the SDN‐POA may begin earlier and terminate sooner in the female than in the male. These differences in neuronal production may partially account for the sexual dimorphism seen in the volume and neuronal number of the SDN‐POA of the adult rat.
Two visual pathways to the telencephalon in the nurse shark (Ginglymostoma cirratum). II. Ascending thalamo‐telencephalic connections
Authors: Luiten Paul G. M. 
Published: January 2005

AbstractAs part of a study on retino‐telecephalic pathways the ascending connections to the telencephalic central nucleus were investigated by retrograde transport of horseradish peroxidase. The central nucleus of the telencephalon, which is the main recipient for input from the brainstem, grossly can be divided into three rostrocaudal parts according to their afferent connections. The rostral third receives input mainly from the contralateral central thalamic nucleus and to a lesser degree from the lateral geniculate nucleus, periventricular gray, and a nucleus called the ventral mesencephalic tegmentum. The middle third of the central nucleus maintains an afferent connection with contralateral lateral geniculate, ventrolateral optic, and central thalamic nucleus, with the ventral mesencephalic tegmentum and periventricular gray bilaterally, and with a group of cells in the superior raphé nucleus. Caudal central nucleus injections of HRP resulted in labeling of cells in the contralateral lateral geniculate nucleus, ventral mesencephalic tegmentum, and central thalamic bilaterally, and in the superior raphé nucleus preoptic area and periventricular gray. From these results it can be concluded that visual information may reach the central telencephalic nucleus by two separate pathways: one pathway from retina via ventrolateral optic nucleus to the middle third of the central nucleus, and a second pathway from retina to optic tectum, which reportedly projects to the lateral geniculate nucleus, which in turn provides afferents to the caudal two‐thirds of the central nucleus. As such the nurse shark's visual system posesses structural features that are homologous to the two visual systems of higher vertebrate groups.
The distribution and sizes of ganglion cells in the retinas of five Australian marsupials
Authors: Tancred Elizabeth 
Published: January 2005

AbstractMaps of ganglion‐cell distribution have been constructed from whole‐mounted retinas of five Australian marsupial species. The pademelon wallaby (Thylogale billiardieri), the scrub wallaby or tammar (Macropus eugenii), and the carnivorous Tasmanian devil (Sarcophilus harissi) have both a visual streak and an area centralis. The retina of the brown bandicoot (Isoodon obesulus) also shows both these features but they are less prominent than in the former three species, whereas the burrow‐dwelling, hairy‐nosed wombat (Lasiorhinus latifrons) possesses a well‐developed visual streak but seems to lack an area centralis.A study of ganglion‐cell sizes comparing nasal and temporal retina, the visual streak, and/or the area centralis was undertaken in each species. Results show that as in the cat, small ganglion cells tend to concentrate in the visual streak. However, the temporal‐nasal differences in cell sizes described in the cat (Stone et al., '80) could be detected only in those marsupials in which an area centralis was clearly recognizable.
A brainstem atlas of catecholaminergic neurons in man, using melanin as a natural marker
Authors: Bogerts Bernhard 
Published: January 2005

AbstractThe present paper provides an atlas showing the distribution of melanin‐containing nerve cells in the human brainstem. It was found that neuromelanin, which can be viewed as a waste product of catecholamine metabolism, is suitable as a natural marker for catecholaminergic neurons in the medulla oblongata, pons, and the mesencephalon of the adult human brain. Within these areas of the brain, there is a striking similarity between the location of melanin and the catecholamine cell bodies described in various animals and in human fetuses, whereas no melanin was found in the diencephalic dopaminergic cell groups. Cell counts from the center of each area showed that the mean density of melanin‐containing perikarya varied considerably between the different areas.
Neuronal plasticity in the deafferented hypothalamic arcuate nucleus of adult female rats and its enhancement by treatment with estrogen
Authors: Matsumoto Akira , Arai Yasumasa 
Published: January 2005

AbstractThe hypothalamic arcuate nucleus (ARCN) was examined ultrastructurally 3 or 21 days after complete deafferentation of the medial basal hypothalamus (MBH) in ovariectomized adult female rats. Axodendritic shaft (SHS) and spine synapses (SPS) were counted in a field of 18,000 μm2 in the middle part of the ARCN in each brain. The mean numbers of SHS and SPS at 3 or 21 days after deafferentation were reduced to about half of those in intact control animals. When the ARCNs of the ovariectomized MBH‐island rats were examined 3 days after treatment with estradiol benzoate (EB, 2 μg/day), the numbers of SHS and SPS did not differ from those in ovariectomized MBH‐island rats without EB treatment. However, EB treatment for 21 days produced a marked increase in the number of both SHS and SPS in the ovariectomized MBH‐island females, with the number of SHS in these females being restored to almost 75% of the intact level; the incidence of SPS was also significantly greater than that in the intact control animals. In these EB‐treated, ovariectomized MBH‐island rats, double synapses (spine‐spine and spine‐shaft double synapses) were frequently observed. In ovariectomized females without MBH deafferentation, however, estrogen failed to increase the numbers of SHS, SPS, and double synapses, which were almost comparable to those in intact and ovariectomized controls.These results suggest that estrogen has a facilitatory effect on SHS and SPS formation in the deafferented ARCN, presumably stimulating not only axonal sprouting but also dendritic spine formation by intact arcuate neurons in the MBH island.
The ratio of preganglionic axons to postganglionic cells in the sympathetic nervous system of the rat
Authors: Brooks‐Fournier Rebecca , Coggeshall Richard E. 
Published: January 2005

AbstractPreviously reported preganglionic‐postganglionic ratios for the sympathetic system are a major part of the evidence for the widely accepted idea that the sympathetic innervation of the viscera is diffuse. Unfortunately, the previous reports did not assess the non‐preganglionic fibers in the nerves examined, and the limitations of light microscopy precluded accurate unmyelinated fiber counts. Thus, a recalculation of these ratios is necessary.The present study recalculates these ratios for the cervical sympathetic system of the rat. All fiber counts are done with the electron microscope which has the resolution necessary for accurately determining axon numbers. Selective surgical procedures establish that 84% of the axons in the cervical sympathetic trunk are preganglionic, 11% are postganglionic, and 5% are sensory. Thus, the numbers of preganglionic fibers can now be accurately assessed and compared to the number of postganglionic neurons in the superior cervical ganglion. When this is done, a preganglionic/postganglionic ratio of approximately 1:4 is obtained. This ratio differs considerably from those previously published.
Viscertopic localization of preganglionic parasympathetic cell bodies of origin of the anterior and posterior subdiaphragmatic vagus nerves
Authors: Dennison S. J. , O'Connor B. L. , Aprison M. H. , Merritt V. E. , Felten D. L. 
Published: January 2005

AbstractUtilizing the retrograde HRP transport method, fibers from anterior and posterior subdiaphragmatic branches of the vagus nerve in the rat were traced to their cells of origin in the brainstem. Efferents to the gut supplied by the subdiaphragmatic vagus nerves derive from cell bodies organized in a viscerotopic, spindle‐shaped longitudinal cell column throughout the longitudinal extent of the classically described dorsal nucleus of the vagus (DNV) and in regions of nucleus commissuralis (NC), caudal to the DNV. This entire longitudinal group of cells is called the DNV cell column. In the caudal one third of the DNV cell column, the cell bodies were found in the midline and paramedian posterior portion of the NC, and in the anterior portion of the caudal DNV, in a horizontally oriented cluster of cells when viewed in cross section. In the middle one third of the DNV cell column, the cell bodies moved laterally, but still maintained their anterior position in the nucleus. In the rostral one third of the cell column, the cell bodies were located at the lateral margin of the DNV. A few scattered cell bodies extended caudally from the DNV cell column into the dorsal region of lamina X of spinal cord, and reached as far caudal as the C5‐C6 segments. The anterior subdiaphragmatic branch of the vagus contained axons whose cell bodies were mainly but not exclusively located in the ipsilateral (left) side of the medulla, while the posterior subdiaphragmatic branch of the vagus contained axons whose cell bodies were found bilaterally in the medulla, with a majority (approx. 60%) located on the ipsilateral (right) side, and approximately 40% located on the contralateral (left) side.
Distribution of dendrites from biventer cervicis and complexus motoneurons stained intracellularly with horseradish peroxidase in the adult cat
Authors: Rose P. K. 
Published: January 2005

AbstractThe three‐dimensional distribution of dendrites from the dorsal neck muscles biventer cervicis (BC) and complexus (CM) was examined in the adult cat using intracellular staining techniques. Motoneurons were electrophysiologically identified, stained with injection of horseradish peroxidase, and reconstructurcted from serial histological sections. The dendritic distributions of all motoneurons examined followed an orderly pattern. Many dendrites extended rostrally and caudally to form a complex parallel collection of dendrites in the ventromedial nucleus. Other dendrites projected dorsolaterally into the spinal accessory nucleus and lateral parts of lamina VII and VIII. Dorsomedial dendrites followed a path parallel to the medial border of the ventral horn and frequently terminated near the central canal. A few scattered dendrites were usually found directly dorsal to the soma in lamina VIII.This pattern of dendritic distribution differed distinctly from the dendritic distribution of motoneurons in other spinal regions. However, in all spinal regions, including the upper cervical spinal cord where BC and CM motoneurons were found, the pattern of dendritic distribution from different motoneurons was similar if their somata were located in the same region.For 15 motoneurons with well‐stained dendrites, the mean rostral‐caudal extent of the dendritic tree was 2,860 μm. The mean total dendritic length of three of these motoneurons measured 73,100 μm, almost four times larger than hindlimb motoneurons involved in planter reflexes. Despite the large size of the dendritic trees of BC and CM motoneurons, the surface areas of BC and CM cell bodies were smaller than most large hindlimb motoneurons. These quantitative differences in motoneuron dimensions may in turn be reflected by differences in the electrotonic properties of motoneurons in different motoneuron nuclei.
Spinocerebellar projections to lobules I and II of the anterior lobe in the cat, as studied by retrograde transport of horseradish peroxidase
Authors: Matsushita Matsuo , Okado Nobuo 
Published: January 2005

AbstractSpinocerebellar tract (SCT) neurons projecting to lobules I and II of the cerebellar anterior lobe were identified by the retrograde horseradish peroxidase technique in the cat. Instead of a conventional stereotaxic approach, we removed ventral parts of the vermis of the posterior lobe and approached the posterior aspect of lobule I through the fourth ventricle. Under direct visual guidance, discrete injections were made into lobule I or lobule II with a glass micropipette.Neurons projecting to lobule I were located mainly in the central cervical nucleus (CCN), the medial part of lamina VII of L6 to the caudal segments, and in lamina VIII of S2 to the caudal segments (with crossed ascending axons). The latter two groups correspond to the medial lamina VII group of the lumbar to the caudal segments and the ventral horn group of the sacral‐caudal segments of our previous studies. A small number of Clarke column neurons (with uncrossed ascending axons) also projected to lobule I. All of these neuronal groups projected to lobule II. In addition, large neurons in lamina V and in the border between laminae IV and V from S2 to the caudal segments projected to sublobule IIA, and more numerously to sublobule IIB (with crossed ascending axons). They belong to the dorsal horn group of the sacral‐caudal segments of our previous studies. Spinal border cells (with crossed ascending axons) projected to sublobule IIB, and a small number, to sublobule IIA. It was suggested that the CCN neurons project more densely to the median region whereas Clarke column neurons project to the lateral part of these lobules.
Short‐ and long‐term effects of neonatal and adult visual cortex lesions on the retinal projection to the pulvinar in cats
Authors: Labar Douglas R. , Berman Nancy E. , Murphy E. Hazel 
Published: January 2005

AbstractAn increased retinal projection to the pulvinar occurred in cats following neonatal ablation of visual cortical areas 17, 18, and 19. After unilateral lesions, the retinopulvinar projection visualized with autoradiography was larger and denser on the lesioned side than on the intact side. This increased projection was first recognized when the lesioned kittens were 1 week old, when increased labeling in the pulvinar was first detected. The retinopulvinar projection on the intact side of the brain decreased in size with age over the first 3 months of life. This decrease in size was not observed on the lesioned side of the brain. The absence of this decrease on the lesioned side may represent a failure of retraction of exuberant connections, but because of the active invasion by retinal fibers immediately after the lesion, observations of the normal retraction may simply be obscured. Severe cellular degeneration in the dorsal lateral geniculate occurred a few days before the changes in the retinopulvinar projection began; this loss of a postsynaptic target for many retinal axons may trigger the reorganization of input to the pulvinar retino‐recipient zone (pulvinar‐RRZ).After adult visual cortex lesions, no reorganization of the retinopulvinar projection took place. The modification of the projection from the retina to the pulvinar that occurs after ablation of visual cortex in the newborn cat may contribute to the sparing of visual abilities seen after these lesions.
Regional differences in fiber size in the cochlear nerve
Authors: Romand R. , Romand M. R. , Marty R. 
Published: January 2005

AbstractThe topographical variations in fiber size in the cochlear nerve of cat were quantitatively studied by electron microscopy. Measurements of fiber size as they appeared at the outlet of the spiral lamina show that fibers originating from the basal part of the cochlea are larger than those from the apex. When the diameter of apical fibers and their axoplasms at two different levels are compared, a significant variation in size is observed. As they appear in the internal acoustic meatus the apical fibers are larger at the level of the nerve trunk compared with the same fibers near the ganglion cell bodies. There are significant differences in fiber diameter with regard to their length for fibers derived from the apical turn. These results are compared with previous findings.