bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of hyaline, border, and vacuole cells in chick inner ear
Authors: Oesterle Elizabeth C. , Cunningham Dale E. , Rubel Edwin W 
Published: January 2005

AbstractThe sense organ for hearing in birds, the basilar papilla, is capable of replacing lost or damaged hair cells and supporting cells through regeneration. Potential candidates for precursor‐cell populations include cells within the auditory receptor epithelium and nonsensory cells inferior to the sensory epithelium. Ultrastructural characteristics of hyaline cells, border cells, and vacuole cells, nonsensory cells which border or lie inferior to the receptor epithelium proper, were studied with transmission electron microscopy. Data were obtained from normal neonatal and adult chickens.Several rows of epithelial cells separate hyaline cells from inferiorly located organ supporting cells and hair cells. Ultrastructural characteristics and location of these epithelial cells differentiate them from organ supporting cells and hyaline cells; consequently, we have termed them „border cells”︁. Synaptic specializations are observed between neural elements and border cells, and gap junctions are found between adjacent border cells, between border cells and neighboring organ supporting cells, and between juxtaposed border and hyaline cells.Hyaline cells, in contrast to border cells, are highly specialized. Dense bundles of filaments are present in hyaline cells from the basal one‐half of the papilla, and an unusual structure, a rough tubular aggregate, is present in hyaline‐cell cytoplasm. Pre‐ and postsynaptic specializations are observed between neural elements and hyaline cells, and gap‐junctional complexes link neighboring hyaline cells.Vacuole cells lie inferior to the hyaline cells and rest on the inferior fibrocartilaginous plate. They are unspecialized morphologically. Their only remarkable morphological feature is the abundance of spherical vacuoles within their cytoplasmic matrix.
Analysis of neuritic outgrowth from severed giant axons inLumbricus terrestris
Authors: Lyckman A. W. , Heidelbaugh S. M. , Bittner G. D. 
Published: January 2005

AbstractThis study analyzes the detailed morphometric pattern at various postoperative times of neuritic outgrowths from the proximal and distal stumps of two uniquely identifiable axons. Morphological patterns of neuritic outgrowths from stumps of severed axons were compared for medial and lateral giant axons in the central nervous system of the earthwormLumbricus terrestris.Outgrowths from proximal and distal stumps were labeled by injection of fluorescent dye into axonal stumps and assessed according to morphometric parameters. Outgrowths from axonal stumps of severed giant axons were statistically indistinguishable for most morphometric measures of neuritic quantity, shape, direction, and location. There were two exceptions to this general rule: 1) proximal stumps of medial giant axons produced significantly more neurites than distal stumps of medial giant axons, and 2) proximal stumps of lateral giant axons produced significantly longer neurites than proximal stumps of medial giant axons. No measure of neuritic outgrowth showed a significant change from the second through seventh postoperative week, suggesting that most outgrowth occurred in the first two postoperative weeks and that neuritic morphology remained stable through the seventh postoperative week. Neurites grew across the lesion site in relatively straight trajectories parallel to the longitudinal axis of the ventral nerve cord and often grew alongside the appropriate axonal stump across the lesion site. The length of neurites growing in close apposition to appropriate axonal stumps or giant axons was much greater than expected, had outgrowth been randomly directed. These data provide a basis for future investigations of the mechanisms that regulate neuritic outgrowth.
Somatic sensory responses in the rostral sector of the posterior group (POm) and in the ventral posterior medial nucleus (VPM) of the rat thalamus
Authors: Diamond Mathew E. , Armstrong‐James Michael , Ebner Ford F. 
Published: January 2005

AbstractThe rodent barrel field cortex integrates somatosensory information from two separate thalamic nuclei, the ventral posterior medial nucleus (VPM) and the rostral sector of the posterior complex (POm). This paper compares the sensory responses of POm and VPM cells in urethane‐anesthetized rats as a first step in determining how cortex integrates multiple sensory pathways.A complete representation of the contralateral body surface was identified in POm. Trigeminal receptive fields (RFs) of POm and VPM cells were mapped by computer‐controlled displacement of individual whiskers; responses were quantified by using peristimulus time histograms. Average RF size was similar in POm (5.1 whiskers) and VPM (4.4 whiskers), but evoked responses in the two nuclei differed significantly according to all other measures. VPM cells were maximally responsive to one single whisker‐the „center RF.”︁ Stimulating this whisker evoked, on average, a response of 1.4 spikes/stimulus at a latency of 7 ms; surrounding whiskers evoked responses of < 1 spike/stimulus at latencies of > 8 ms. In contrast, POm cells were nearly equally responsive to several whiskers. Quantitative criteria allowed us to designate a single whisker as the „center RF”︁ and stimulating this whisker evoked, on average, a response of 0.5 spikes/stimulus at a latency of 19 ms. VPM cells, but not POm cells, were able to „follow”︁ repeated whisker deflection at > 5 Hz.We conclude that, when a single whisker is deflected, VPM activates the related cortical barrel‐column at short latency— before the onset of activity in POm. The timing of activation could allow POm cells to modulate the spread of activity between cortical columns.
Evaluation of neural fold fusion and coincident initiation of spinal cord occlusion in the chick embryo
Authors: Desmond Mary E. , Field Marcia C. 
Published: January 2005

AbstractAlthough it is known that rapid expansion of the vertebrate brain begins near the time that the spinal neurocoel is occluded, it still remains unknown when occlusion occurs in relation to neurulation. Since both morphogenetic events are critical for normal brain growth, it is important to decipher the temporal relationship between the two processes. This study assessed the temporal relationship of the two events with the rationale that if it could be demonstrated that occlusion occurs coincident with the completion of neurulation, then it could be argued that factors shown to direct neurulation could also initiate occlusion. Nearly 600 chick embryos (stages 9− through 12+) were cultured atop egg‐agar, the caudal extent of neurulation determined, the cranial five pairs of somites removed and the neurocoels assessed for occlusion. In stage 9− through 10− chicks, neurulation of the spinal cord is incomplete. Stages 10 through 12+ exhibit neurulation and occlusion from the 8th to 19th somites. When lateral tissues were removed in embryos 8 through 10−, the neural folds became dysraphic whereas in embryos stage 10 and older, the folds remained fused dorsomedially and occluded. The only surgical manipulation that was found to prevent occlusion was elimination of the lateral tissues responsible for elevation and closure of the neural folds. Analysis of particular components of the lateral tissues essential for convergence, by treating embryos (n = 75) with chemicals known to degrade tissue‐tissue bonds or specific components of the perineural matrix, indicated that more than 75% of the embryos treated with EDTA, EDTA plus Ca2+, trypsin, collagenase, or hyaluronidase exhibited little or no effect on convergence, dorsomedial fusion, and concomitant occlusion. © 1992 Wiley‐Liss, Inc.
Nerve growth factor receptor immunoreactivity in neurons of the normal adult rat spinal cord and its modulation after peripheral nerve lesions
Authors: Rende Mario , Hagg Theo , Manthorpe Marston , Varon Silvio 
Published: January 2005

AbstractMotoneurons of the rat spinal cord express low‐affinity nerve growth factor receptor (LNGFR) and corresponding mRNA during development, and re‐express it after their axotomy by peripheral nerve injury. The present study establishes the anatomical and quantitative baseline of LNGFR immunoreactive (LNGFR‐IR) neurons of the entire normal adult female rat and then investigates the temporal course for the re‐expression of LNGFR‐IR in lumbar motoneurons after either a crush lesion (which is followed by regeneration and reconnection to the muscle) or a cut lesion with removal of the distal stump (where a neuroma but no reconnection is formed). In the normal adult spinal cord, two types of LNGFR‐IR neurons were recognized: (1) small populations of large motoneurons located in the ventral horn mainly in correspondence to the regions of the phrenic, cremasteric and dorsolateral nuclei, and (2) a more numerous and more dorsally located population of small neurons. With a sciatic cut lesion, the number of LNGFR‐IR motoneurons at spinal levels L4–L6 rapidly and dramatically increased to a maximum between post‐lesion days 1 and 7, apparently involving most axotomized motoneurons of the region, and returned to the baseline level by day 30. With a crush lesion, similar numbers and virtually the same time‐course of LNGFR‐IR appearance were seen, but the onset of progressive disappearance of LNGFR‐IR neurons was delayed by one week, so that at 30 days, the most caudal motoneurons (which are last to reach their target) were still LNGFR‐IR. Comparison of these two time courses gives clues to the kind of signals that may be involved in initiating and/or maintaining the LNGFR response. © 1992 Wiley‐Liss, Inc.
Intrinsic and commissural connections of the rat inferior colliculus
Authors: Saldaña Enrique , Merchań Miguel A. 
Published: January 2005

AbstractThis study analyzes the distribution of the intrinsic and commissural fiber plexuses originating in the central nucleus of the inferior colliculus in the rat. The anterograde tracer Phaseolus vulgaris‐leucoagglutinin (PHA‐L) was injected iontophoretically at different places along the tonotopic axis of the central nucleus and visualized immunohistochemically. In coronal sections the terminal fields of axons originating at each injection site are seen to create four well‐defined bands across the rostrocaudal extent of the inferior colliculus, two in the ipsilateral and two in the contralateral side. The “ipsilateral main band” extends dorsomedially and ventrolaterally from the injection site, in register with the known isofrequency contours of the central nucleus, spanning this nucleus and extending into the dorsal cortex of the inferior colliculus. The “ipsilateral external band” is located in the external cortex, where it is oriented dorsoventrally, slightly oblique to the pial surface. In caudal sections, the ventral portion of these two bands appear to join. The two bands in the contralateral inferior colliculus occupy a symmetric position to those of the ipsilateral side, forming a mirror‐like image. The position of the four bands changes as the position of the injection site is varied along the frequency gradient axis of the central nucleus. After ventromedial (high frequency area) injections, the main band is ventral and medial, and the external band ventral and lateral. After more dorsolateral (lower frequency) injections, the main band is more dorsal and lateral, whereas the external band is more dorsal but more medial. Thus, the change in the position of the external band is separate and opposite to that of the main band. We suggest that the main bands represent isofrequency contours. Since the projection from the central nucleus to the external cortex of the inferior colliculus also appears to be tonotopic, we also propose a tonotopic organization for the external cortex. The main bands overlap the terminal field of the lemniscal fibers in the central nucleus; thus, it is concluded that the intracollicular fibers contribute to the formation of the known fibrodendritic laminae of the central nucleus.A possible role in preservation of frequency information and integration of other different acoustic parameters is proposed for the main bands. The external bands could participate in polysensory integration, and the commissural connections could be involved in hitherto unknown stages of binaural processing of sound.Based on our results, several modifications are proposed for delineating the subdivisions of the inferior colliculus. © 1992 Wiley‐Liss, Inc.
Embryonic development of a population of spiking local interneurones in the locust (Schistocerca gregaria)
Authors: Shepherd David , Laurent Gilles 
Published: January 2005

AbstractWe examined the embryonic development of an identified group of thoracic spiking local interneurones in the locust. These interneurones are primary integrators of mechanosensory information from the legs and make inhibitory output connections with motor neurones, nonspiking local interneurones, and intersegmental interneurones. Using intracellular dye injection, we traced the origins of these interneurones and described their morphological development. All of the interneurones in this population are produced by neuroblast NB4‐1. The interneurones are produced during the latter stages of the neuroblast lineage and could not be identified before 55% development. Their growth could be divided into three distinct phases: first, a period of initial outgrowth (55–70%) during which the basic skeleton of major neurites is formed; second, a shorter period of rapid growth (70–80%) during which the basic skeleton is elaborated by the addition of many side branches; and third, a period of maturation (80–95%) during which the branches formed during earlier growth appear to be pruned. The possible implications of these results for neural development and synaptogenesis are discussed. © 1992 Wiley‐Liss, Inc.
Anatomical organization of the brainstem octavolateralis area of the oyster toadfish, Opsanus tau
Authors: Highstein Stephen M. , Kitch Rusty , Carey John , Baker Robert 
Published: January 2005

AbstractAnatomical studies were undertaken to analyze the brainstem organization of the auditory, vestibular, and lateral line nuclei in a teleost, the oyster toadfish, Opsanus tau. Neuronal cytoarchitectonics and horseradish peroxidase label of cranial nerves were utilized to delineate the borders of the five octavus and two lateralis brainstem nuclei. Each of the eight octavolateralis nerves were labeled individually to compare and contrast their central projections. Projections of the three semicircular canals were found to be largely overlapping. Terminal fields were observed within the eminentia granularis and in each of the octavus nuclei. The nucleus anterior octavus was reciprocally innervated by the semicircular canals and the saccule. The canals terminated heavily in the ventral portions of the anterior octavus, whereas the saccule terminated extensively in the dorsal nuclear portions. The saccule also distributed terminals throughout the octavus cell column, including a light terminal field within the dorsal, medial, and anterior portions of the descending octavus nucleus, a region densely innervated by this end‐organ in other species. These results suggest that the anterior octavus nucleus may have a dual function. The dorsal portions may be an auditory relay nucleus, whereas the ventral portions may subserve vestibular function. Utriclar and lagenar afferents also terminated throughout the octavus cell column. Afferents of the anterior and posterior lateral lines ended within the eminentia granularis and the lateral line nuclei. Semicircular canal afferents and lateral line afferents appeared completely segregated within the eminentia. The above results are useful as an aid in the understanding of an ongoing, comprehensive functional analysis of auditory and vestibular mechanisms in toadfish and complement previous work on the efferent vestibular and sound‐producing motor systems. Examination of toadfish contributes to a more general and complete overview of the octavolateralis area of teleosts and the eventual identification of primitive and derived patterns of octaval organization. Additionally, this work may permit the further demonstration of species‐typical characters that may indicate adaptations to particular behavioral repertoires.
The calcium binding proteins parvalbumin and calbindin‐D 28K form complementary patterns in the cat superior colliculus
Authors: Mize R. Ranney , Luo Qian , Butler Grace , Jeon Chang‐Jin , Nabors Burt 
Published: January 2005

AbstractParvalbumin (PV) and calbindin‐D 28K (CaBP) are calcium binding proteins involved in calcium regulation in the brain. In some regions they coexist in the same neuron, while in other regions they are found in different cell types. We have studied the distribution and morphology of PV labeled neurons in the cat superior colliculus (SC) with antibody immunocytochemistry and compared this labeling to that of CaBP. PV neurons were concentrated in a dense tier within the deep superficial gray and upper optic layers. Scattered PV neurons also were found within the deep layers of SC. By contrast, CaBP neurons were concentrated in three tiers: one within the zonal and upper superficial gray layers, a second within the deep optic and upper intermediate gray layers (IGL), and a third within the deep gray layer. The distribution of PV neurons is thus complementary to that of CaBP neurons, with the CaBP cell tiers bordering the dense tier of PV neurons.PV neurons varied in size and morphology. The average diameter of labeled cells was 20 μm, almost twice the size of CaBP neurons. The cells were predominantly round, vertical fusiform, or stellate, and included the very large neurons found scattered in the IGL. Horseradish peroxidase injections into the lateral geniculate nucleus, the lateral posterior nucleus, the opposite superior colliculus, the dorsal lateral pontine gray nucleus, and two descending pathways—the crossed predorsal bundle and the tecto‐ponto‐bulbar tracts—each labeled SC neurons that were also labeled by PV. A large percentage (84%) of projection neurons contained PV. This result also differs from CaBP neurons in SC, most of which are interneurons. Two antigen double‐label experiments did not produce any cells that contained both PV and CaBP. The two calcium binding proteins thus reveal a unique sublaminar organization in SC that consists of alternating small cell interneuron groups and large cell projection neuron groups.
Changes of chemoarchitectural organization of the rat spinal cord following ventral and dorsal root transection
Authors: Hirakawa Makoto , Kawata Mitsuhiro 
Published: January 2005

AbstractTime‐related changes in the distribution of chemical messengers in the rat spinal cord following the transection of dorsal and ventral roots were observed by using immunohistochemistry for the following antigens: microtubule‐associated protein 2 (MAP2), calcitonin gene‐related peptide (CGRP), substance P (SP), galanin (Gal), Met‐enkephalin (Enk), neuropeptide Y (NPY), and serotonin (5‐HT). To investigate dendrocytoarchitectonic organizational changes, morphometric analyses were performed on both the gray and the white matter of tissue samples stained with MAP2 antiserum. A significant reduction in the area of gray matter on the lesioned side was seen from 1 to 24 weeks postoperation, and progressive changes in the shape of the gray matter were also observed. CGRP‐immunoreactive fibers were reduced in number in the posterior horn after root transection, except in the lateral part of lamina I. In contrast, CGRP immunoreactivity in the anterior horn cells of the ipsilateral side was increased early after transection, but later it progressively decreased. Root transection also caused significant reduction in the number of SP‐immunoreactive fibers in the posterior horn, but no changes were seen in the anterior horn. Gal immunoreactivity was also affected by root transection, and it changed in a similar way to CGRP immunoreactivity. 5‐HT‐immunoreactive fibers were increased in the posterior horn after transection, and later decreased. In the anterior horn, there were no changes in the intensity or distribution pattern of 5‐HT‐immunoreactive nerve fibers following root transection. Enk and NPY immunoreactivity in the anterior and posterior horns was not affected by root transection up to 24 weeks postoperative. These results show that spinal root transection caused significant changes in the chemoarchitectural organization of nerve fibers containing certain types of chemical messengers, such as CGRP, SP, Gal, and 5‐HT, in addition to altering dendritic geometry in the spinal cord.
Effects of prenatal ethanol exposure on the development of Bergmann glia and astrocytes in the rat cerebellum: An immunohistochemical study
Authors: Shetty Ashok K. , Phillips Dwight E. 
Published: January 2005

AbstractThe consequences of prenatal ethanol exposure on the postnatal development of Bergmann glia and astrocytes in the rat cerebellum were investigated by using glial fibrillary acidic protein (GFAP) immunolabeling. Pregnant rats were either fed with an ethanol containing liquid diet (6.7% v/v) or pair‐fed with an isocaloric diet throughout gestation. On postnatal day (PD) 15 and 22, parasagittal sections of the cerebellar vermis from female offspring were processed for GFAP immunohistochemistry to assess the development of Bergmann glia and astrocytes in lobules I, VII, and X and astrocytes in the central core of white matter. On PD 15, compared to control animals, ethanol exposed animals had fewer GFAP positive Bergmann glial fibers per unit length of molecular layer; a significantly greater percentage of morphologically immature Bergmann fibers; a significantly greater GFAP positive astrocytic area per unit area of internal granular layer and central white matter; and the astrocytic processes were wider and more closely packed. These glial changes were associated with significantly thicker external granular layer in all 3 lobules. However, no significant differences were seen between the ethanol exposed and control animals on PD 22, indicating “catch‐up growth” in the ethanol exposed animals during the third postnatal week. These results suggest that prenatal ethanol exposure causes (1) delayed maturation of Bergmann glia, which in turn contributes to the delayed migration of granule cells; and (2) alterations in the normal postnatal development of astrocytes. © 1992 Wiley‐Liss, Inc.