bluuebunny/crossref_metadata_2025_split huggingface dataset:
Normal and precocious sprouting of heat nociceptors in the skin of adult rats
Authors: Doucette R. , Diamond J. 
Published: January 2005

AbstractThe ability of intact cutaneous thermonociceptive C fibers to sprout into adjacent denervated skin, and the effects on this of electrical activity in the axons, were studied in adult rats. The presence of heat‐sensitive endings in the back skin was assessed physiologically by the ability of a hot probe to elicit the reflex contraction of the underlying cutaneus trunci muscle; sensory C fibers were detected both by the Evans Blue technique, in which antidromic excitation of the C fibers causes a visible extravasation of dye in the skin it supplied, and by direct electron microscope (EM) examination of skin. The field of an identified branch of a selected dorsal cutaneous nerve (DON) was “isolated” by eliminating all the nerves supplying the surrounding skin.The heat‐sensitive area began to expand between 10 and 14 days after its isolation and reached a maximum (approximately doubling the initial value) by about 24 days. When the isolated nerve was antidromically excited, the borders within which dye extravasation now occurred had extended; the area of discoloration correlated well with that of the (enlarged) heat field, showing that its expansion was indeed attributable to C fiber sprouting. Electron microscopic examination showed that some of the “empty” Schwann tubes, routinely observed in the subepidermal horizontal fiber system of insensitive skin following denervation, had acquired unmyelinated axons when heat sensitivity had returned. A precocious expansion of the heat field, which was obvious by 10 days after its isolation, was produced if the heat stimulus was applied randomly throughout the field at the time of the adjacent denervations; this expansion too was shown to be due to sprouting of C fibers. Precocious sprouting of heat‐nociceptive fibers also occurred if, immediately following the field isolation, the C fibers in the spared DCN were electrically excited, and also if pinches were applied throught its field, i.e., the C fibers involved seemed to be polymodal, responding both to heat and to noxious mechanical stimulation. Precocious sprouting did not occur when tetrodotoxin was used to block central conduction of the “conditioning” impulses in the isolated DCN. Peripheral nerve damage often occurs in a situation likely to cause activation of nociceptive nerves; we suggest that the accelerated sprouting of spared axons could be important in reducing the period during which atrophic changes might occur in denervated target regions, in addition to hastening the provision of a nociceptive innervation. The various experimental approaches now available for producing differential innervation of selected regions of back skin are summarized.
Amygdaloid connections with posterior insular and temporal cortical areas in the rat
Authors: McDonald Alexander J. , Jackson Thomas R. 
Published: January 2005

AbstractThe connections of the amygdala with the insular and temporal cortices were examined by injecting wheat germ agglutinin conjugated to HRP (WGA‐HRP) into the rat cortex. Following injections into the posterior agranular insular area (AIp) or perirhinal cortex (PR), bands of labeled neurons extending across nuclear boundaries were observed in the amygdala. These neuronal bands involved cells in the lateral, basolateral, and basomedial nuclei as well as the periamygdaloid cortex. Other nuclei of the corticomedial amygdala and the ventral endopiriform nucleus also exhibited retrogradely labeled cells. Anterograde label was observed in nuclei containing labeled neurons and in the central nucleus. Injections into gustatory, somatosensory, and auditory neocortical areas located dorsal to AIp and PR labeled small numbers of cells in the lateral and basolateral nuclei. Injections into AIp, PR, and, to a lesser extent, dorsally adjacent neocortical areas produced both retrograde and anterograde labeling in the contralateral amygdala. The main nuclei with contralateral insular and temporal projections are the basomedial nucleus, ventral endopiriform nucleus, and nucleus of the lateral olfactory tract. The contralateral central nucleus and to a lesser extent the lateral nucleus exhibited anterograde labeling.The pattern of retrograde labeling seen with injections at different rostrocaudal levels of the AIp‐PR continuum indicates that amygdalocortical projections to these areas exhibit an overlapping topographical organization. Comparison of the results of this study with findings on amygdaloprefrontal cortical efferents suggests that amygdaloid projections to the entire fronto‐insulo‐temporal mesocortical field are topographically organized.
Sources of projections to subdivisions of the inferior colliculus in the rat
Authors: Coleman James R. , Clerici William J. 
Published: January 2005

AbstractBrainstem and forebrain projections to major subdivisions of the rat inferior colliculus were studied by using retrograde and anterograde transport of horseradish peroxidase. Retrograde label from injection into the external cortex of the inferior colliculus appears bilaterally in cells of the inferior colliculus, as well as in other brainstem auditory groups including the ipsilateral dorsal nucleus of the lateral lemniscus and contralateral dorsal cochlear nucleus. The external cortex is the only collicular subdivision where an injection labels cells in the contralateral cuneate nucleus, gracile nucleus, and spinal trigeminal nucleus. Other projecting cells to the external cortex are found in the lateral nucleus of substantia nigra, the parabrachial region, the deep superior colliculus, the midbrain central gray, the periventricular nucleus, and area 39 of auditory cortex. Injection of the dorsal cortex of inferior colliculus heavily labels pyramidal cells of areas 41, 20, and 36 of the ipsilateral neocortex. Anterograde label from a large injection of auditory cortex is densely distributed in the dorsal cortex, lesser so in the external cortex., and only slightly in the central nucleus. Labelled cells appear in the central nucleus, dorsal cortex, and external cortex, primarily ipsilaterally, following dorsal cortex injection. Relatively few cells from other brainstem auditory groups show projections to the dorsal cortex. Injection of the central nucleus of the inferior colliculus results in robust labelling of nuclei of the ascending auditory pathway including the anteroventral, posteroventral, and dorsal cochlear nuclei (mainly contralaterally), and bilaterally the lateral superior olive, lateral nucleus of the trapezoid body, dorsal nucleus of the lateral lemniscus, and the central nucleus, dorsal cortex, and external cortex of the colliculus. The medial superior olive, superior paraolivary nucleus, and ventral nucleus of the trapezoid body essentially show ipsilateral projections to the central nucleus. The differential distribution of afferents to the inferior colliculus provides a substrate for functional parcellation of collicular subdivisions.
Defects of the fetal forebrain in mice with hereditary agenesis of the corpus callosum
Authors: Wahlsten Douglas 
Published: January 2005

AbstractInbred BALB/c mice are genetically the same, yet less than half of adults show absent or small corpus callosum. Is this because only a minority has prenatal defects of the sling at the telencephalic midline, or do most fetuses have a defective sling but some are able to form a corpus callosum via some other substrate pathway? This question was addressed by comparing large samples of BALB/c fetuses at 17, 18, and 19 days after conception with a series of normal C57BL/6 and hybrid fetuses matched for body size.At 17 days postconception almost all BALB/c fetuses show an unusual widening or bulge in the interhemispheric fissure anterior to the hippocampal commissure. Furthermore, formation of the hippocampal commissure is greatly retarded, although it eventually attains a normal size in adult mice. At 17 days, when mice of normal strains all have a corpus callosum at midplane, almost every BALB/c fetus lacks the structure, but 1 day later 67% of fetuses show delayed formation of this structure and by 19 days all but 7% of fetuses have some callosal axons crossing the midsagittal plane. Many BALB/c fetuses are able to form a corpus callosum without the benefit of a normal sling. The degree of delay of axon crossing is strongly correlated with the severity of sling defects. An unusually small adult corpus callosum occurs because fetal axons are able to follow unusual pathways and actively compensate for absence of the sling, not because of arrested midline development.
Extra‐ and intracellular HRP analysis or the organization of extraocular motoneurons and internuclear neurons in the guinea pig and rabbit
Authors: Evinger Craig , Graf Werner M. , Baker Robert 
Published: January 2005

AbstractThe distribution of extraocular motoneurons and abducens and oculomotor internuclear neurons was determined in guinea pigs by injecting horseradish peroxidase (HRP) into individual extraocular muscles, the abducens nucleus, the oculomotor nucleus, and the cerebellum. Motoneurons in the oculomotor nucleus innervated the ipsilateral inferior rectus, inferior oblique, medial rectus, and the contralateral superior rectus and levator palpebrae muscles. Most motoneurons of the trochlear nucleus projected to the contralateral superior oblique muscle although a small number innervated the ipsilateral superior oblique. The abducens and accessory abducens nuclei innervated the ipsilateral rectus and retractor bulbi muscles, respectively. The somata of abducens internuclear neurons formed a cap around the lateral and ventral aspects of the abducens nucleus. The axons of these internuclear neurons terminated in the medial rectus subdivision of the contralateral oculomotor nucleus. At least two classes of guinea pig oculomotor internuclear interneurons exist. One group, located primarily ventral to the oculomotor nucleus, innervated the abducens nucleus and surrounding regions. The second group, lying mainly in the dorsal midline area of the oculomotor nucleus, projected fee the cerebellum.Intracellular staining with HRP demonstrated similar soma‐dendritic organization for oculomotor and trochlear motoneurons of both guinea pigs and rabbits. Dendrites of oculomotor motoneurons radiated symmetrically from the soma to cover approximately one‐third of the entire nucleus, and each motoneuron sent at least one dendrite into the central gray overlying the oculomotor nucleus. In both species, a small percentage of oculomotor motoneurons possessed axon collaterals that terminated both within and outside of the nucleus. The dendrites of trochlear motoneurons extended into the medial longitudinal fasciculus and the reticular formation lateral to the nucleus.Our data on the topography of motoneurons and internuclear neurons in the guinea pig and soma‐dendritic organization of motoneurons in the guinea pig and rabbit show that these species share common organizational and morphological features. In addition, comparison of these data with those from other mammals reveals that dendritic complexity (number of dendrites per motoneuron) of extraocular motoneurons exhibits a systematic increase with animal size.
Viscerotopic representation of the upper alimentary tract in the medulla oblongata in the rat: The nucleus ambiguus
Authors: Bieger Detlef , Hopkins David A. 
Published: January 2005

AbstractThe nucleus ambiguus has been reported to innervate various thoracic and abdominal viscera in addition to the musculature of the upper alimentary tract. However, the literature is contradictory as to how different regions of the nucleus ambiguus innervate specific organs. Therefore, a systematic investigation of the viscerotopic organization of the nucleus ambiguus was undertaken. In 102 rats, 0.5–10.0 μl of HRP, WGA‐HRP, cholera toxin‐HRP or fluorescent tracers were injected into the IXth, Xth, and XIth cranial nerves and the major branches of the Xth as well as organs supplied by them.The results demonstrate that the nucleus ambiguus in the rat is made up of two major longitudinal divisions: a dorsal division comprised of three rostrocaudally aligned subdivisions representing the special visceral efferent component, and a ventral division comprised of at least two subdivisions representing the general visceral efferent component. The dorsal division corresponds to the nucleus ambiguus in the narrow sense and comprises a rostral esophagomotor compact formation, an intermediate pharyngolaryngomotor semicompact formation, and a caudal laryngomotor loose formation. Each of these formations displays a characteristic dendroarchitecture. The stylopharyngeal and cricothyroid motoneurons are displaced rostrad from the main pharyngeal and laryngeal motoneuronal pools. Thyropharyngeal (lower constrictor) motoneurons occupy the rostral half of the semi‐compact formation and hyopharyngeal (middle constrictor) motoneurons its entire length. The ventral division of the nucleus ambiguus corresponds to the external formation, extends along the entire length of the medulla oblongata, and contains preganglionic neurons innervating the heart and supradiaphragmatic structures innervated by the glossopharyngeal and the superior laryngeal nerves.
Alpha ganglion cells in the rabbit retina
Authors: Peichl Leo , Buhl Eberhard H. , Boycott Brian B. 
Published: January 2005

AbstractIn the rabbit retina a distinctive morphological class of large ganglion cells was demonstrated by a combination of intracellular staining with Lucifer Yellow and the quantification of reduced silver‐stained preparations. The class is called alpha because of the qualitative and quantitative resemblance to the alpha cells of the cat's retina. Rabbit alpha cells change their size with location on the retina. In the high ganglion cell density region of the visual streak, their somata are about 15 μ in diameter, and their dendritic fields have diameters as small as 180–220 μm. The largest alpha cells in the inferior periphery have soma diameters of 30 μm and dendritic field diameters of 960 μm. There is a considerable scatter of sizes at any retinal location. Alpha cell density changes from about 55/Inm2 in the streak to about 3/mm2 in far periphery, and the cells make up 1–1.4% of the ganglion cell population. Dendritic trees stratify in either an inner or an outer sublamina of the inner plexiform layer, suggesting an on/off dichotomy in the response to light. Each of the inner and outer branching subtypes is distributed in a regular mosaic, and the dendritic trees cover the retina completely and economically. The possibility is discussed that the alpha cells are the brisk transient/Y cells of physiology.
Noradrenergic projections to brainstem nuclei: Evidence for differential projections from noradrenergic subgroups
Authors: Grzanna Reinhard , Chee Won K. , Akeyson Edward W. 
Published: January 2005

AbstractRetrograde transport of the fluorescent tracer True Blue was used in combination with immunohistochemical staining of dopamine‐β‐hydroxylase (a marker protein for noradrenergic neurons) to determine the origin of noradrenergic projections to three cranial nerve nuclei: (1) the motor nucleus of the trigeminal nerve, (2) the motor nucleus of the facial nerve, and (3) the spinal trigeminal nucleus pars interpolaris. Noradrenergic cells in the rat brainstem were divided into sub groups and their numbers were determined in serial sections stained with an antiserum to rat dopamine‐β‐hydroxylase. Following tracer injections into the three brainstem nuclei, retrogradely labeled noradrenergic neurons were counted and the percentage of True Blue‐labeled noradrenergic cells in each subgroup was calculated.Injections of tracer into the three cranial nerve nuclei resulted in distinctly different labeling patterns of noradrenergic cells. Of the total number of norepinephrine neurons projecting to the motor nucleus of the trigeminal nerve, 68% were observed within the A7 cell group; 75% of those innervating the motor nucleus of the facial nerve were found in the A5 cell group, and 65% of those projecting to the spinal trigeminal nucleus pars interpolaris were present in the locus ceruleus and subceruleus. These findings indicate that norepinephrine cells in the rat brainstem do not constitute a homogeneous population of cells but that several discrete systems can be identified that differ not only in topography but also in the terminal distribution of their axons. This combined retrograde transport‐immunohistochemical study reveals a much higher degree of topographic order in the projections of norepinephrine neurons than has previously been recognized, The observation of differential projections of noradrenergic subgroups argues against the notion of a global influence of these cells over functionally diverse areas of the brainstem.
Topographical organization of olivocerebellar and corticonuclear connections in the rat—An WGA‐HRP study: I. Lobules IX, X, and the flocculus
Authors: Bernard Jean‐François 
Published: January 2005

AbstractThe organization of the olivocerebellar and corticonuclear relations for vermal lobules IX and X and the flocculus has been studied in the rat by using microinjections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP). This axonal tracer allowed us to study simultaneously the olivocortical connections (revealed by retrograde transport) and corticonuclear connections (revealed by anterograde transport) from a single injection in the cerebellar cortex.The results indicate that four modules can be distinguished, each of which consists of a region of cerebellar cortex receiving afferents from a single small region of the inferior olive (IO) and sending efferents to one or several portions of the cerebellar nuclei and/or vestibular nuclei.The first module includes a medial part of lobule X as well as all the flocculus. It receives afferents from the dorsal cap (dc) and sends efferents to the small cell (s) zone of the dentate nucleus as well as to the medial vestibular (VM) nucleus and subnucleus y.The second module includes a medial parasagittal region located in lobules IX and X. It receives afferents from the ventrolateral outgrowth (vlo) and/or beta nucleus (vlo+beta nucleus) and sends efferents principally to the ventrolateral part of fastigial nucleus and to the superior vestibular (VS), inferior vestibular (VI), and VM nuclei.The third module includes a lateral parasagittal region in lobules IX and X. It receives afferents from the dorsomedial cell column (dmcc) of 10 and sends efferents principally to the interpositus nucleus and subnucleus y.The fourth module includes the most lateral part of lobules IX and Xa. It receives afferents from the principal olive (PO) and sends efferents to the s zone of the dentate nucleus.These results are comparable to those obtained in the cat although a few differences are discussed.
Projections to the inferior colliculus from the anteroventral cochlear nucleus in the cat: Possible substrates for binaural interaction
Authors: Oliver Douglas L. 
Published: January 2005

AbstractThe projections to the inferior colliculus of the cat are shown in autoradiographs after injections of 3H‐amino acids into the anteroventral cochlear nucleus and anterograde axonal transport. Labeled bands of axons are seen in the central nucleus of the inferior colliculus, parallel to the fibrodendritic laminae, and in layers 3 and 4 of the dorsal cortex. A bilateral projection to the lateral, low‐frequency part of the inferior colliculus is observed. In contrast, the more ventromedial, mid‐ and high‐frequency parts receive only a contralateral input. The projections from the cochlear nucleus to both the contralateral midbrain and bilaterally to the superior olivary complex appear to be tonotopically organized. After HRP injections in the inferior colliculus, small numbers of stellate neurons are labeled in the lateral and ventral low‐frequency parts of the anteroventral cochlear nucleus on the ipsilateral side. EM autoradiographs show labeled axonal endings from both sides of the anteroventral cochlear nuclei are present in the same proportion in pars lateralis. Axonal endings from either cochlear nucleus have small, round synaptic vesicles and make asymmetric synaptic contacts on dendrites. Axons from the contralateral side also make axosomatic contacts on large disc‐shaped or stellate cells. Neurons from the ipsilateral anteroventral cochlear nucleus apparently make more synaptic endings per cell as compared to neurons from the contralateral side. Together, bilateral inputs from the anteroventral cochlear nucleus can account for a third of the endings with round synaptic vesicles in pars lateralis of the central nucleus.Morphological similarities among the ascending inputs to the inferior colliculus are discussed. Both direct circuits from the cochlear nucleus to the inferior colliculus and indirect circuits via the superior olivary complex or lateral lemniscus may display banding patterns, nucleotopic organization, or differential synaptic organization. The direct inputs from the anteroventral cochlear nucleus to the colliculus may influence binaural interactions which occur in the superior olivary complex. In addition, direct inputs may create new binaural responses in the inferior colliculus that are independent of lower centers.
Disappearance of Rohon‐Beard neurons from the spinal cord of larval Xenopus laevis
Authors: Lamborghini Janet E. 
Published: January 2005

AbstractRohon‐Beard neurons are primary sensory cells located in the spinal cord of embryonic lower vertebrates. The kinetics of their normal, gradual, but complete disappearance in Xenopus tadpoles has been followed. Levels of acid phosphatase activity, a common histochemical correlate of cell death, were assayed and found to increase at the time of onset of disappearance of Rohon‐Beard cells. Ultrastructural examination revealed the presence of numerous secondary lysosomes, swelling of endoplasmic reticulum and mitochondria, and a decrease in nuclear density. The disappearance of Rohon‐Beard neurons may be attributed to autophagic cell death involving lysosomal acid hydrolases. This process begins only a few days after the maturation of voltage‐ and neurotransmitter‐dependent membrane conductances and the electrical uncoupling of these neurons. The loss of Rohon‐Beard neurons in embryos whose development was arrested by crowding was appropriate for the developmental stage of the animals rather than their chronological age.
Monoclonal antibody reveals radial glia in adult avian brain
Authors: Alvarez‐buylla Arturo , Buskirk Daniel R. , Nottebohm Fernando 
Published: January 2005

AbstractAn antibody prepared against adult canary brain, 40E‐C, stains ventricular zone cells that send long, unbranched processes into the forebrain parenchyma. We identify these cells as radial glia. The same antibody also stains a subset of brain astroglia and reacts with nonbrain material such as mesenchyme, Sertoli cells, and the Z‐line of muscle. A weaker reaction is given by erythrocytes and some endothelial cells. 40E‐C also reacts with the radial glia of the developing rat brain but fails to show any such glia in adult rodent brain. Western blot analysis shows that this antibody recognizes vimentin, a molecule shared by all 40E‐C‐positive cell types. We believe that the presence of radial glia in the adult avian forebrain and their apparent absence in mammals is related to neurogenesis in adulthood, which occurs in birds and much less or not at all in mammals. In addition, the presence of radial glia in adult birds may also relate to other, stillhypothetical, differences in the physiology of adult avian and mammalian brains.