bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative light and scanning electron microscopic study of the developing auditory organs in the bullfrog: Implications on their functional characteristics
Authors: Shofner William P. , Feng Albert S. 
Published: January 2005

AbstractDuring postmetamorphic development in the bullfrog, there is a downward shift in the distributions of best excitatory frequencies (BEFs) of the three populations of primary auditory fibers. This decrease in BEF distribution suggests that concurrent morphological changes occur in the peripheral auditory system during postmetamorphic growth.The postmetamorphic development of the auditory organs in the bullfrog was quantitatively investigated with light and scanning electron microscopy. In the basilar papilla, there are dramatic increases in the lumen volume, contact membrane area, and mass of the tectorial membrane (TM). The area of the sensory epithelium and the total number of hair cells also increase slightly. In the amphibian papilla, the mass of the TM is spatially graded in a step‐wise fashion along the length of the organ in both juvenile and adult bullfrogs, but there is an increase in the absolute mass of the TM throughout the papilla with age. The height of the tallest stereocilia of the predominant hair cell type systematically decreases caudally in the juvenile amphibian papilla, but is uniform throughout the adult papilla. The increase in stereociliary height in the caudal end of the organ presumably results in a decrease in stereociliary stiffness with postmetamorphic age. The length of the amphibian papilla sensory epithelium and the number of hair cells also increase during postmetamorphic development. Theoretically, the observed morphological changes alter the micromechanical tuning properties of the auditory organs so that there is a decrease in the BEFs of the auditory fibers that innervate the two papillae.
Retinal synapses of the cat medial interlaminar nucleus and ventral lateral geniculate nucleus differ in size and synaptic organization
Authors: Mize R. Ranney , Horner Linda H. 
Published: January 2005

AbstractThe retinal terminals of the medial interlaminar nucleus (MIN) and ventral lateral geniculate nucleus (VLG) have been examined quantitatively to determine if there are morphological differences in their synaptic ultrastructure which reflect their distinctive physiologies. The cross‐sectional area and density (number per unit area) of synaptic contact zones with conventional and presynaptic dendrites (F2 profiles) were measured for each retinal terminal. The densities of F2 presynaptic dendrites and F1 flattened vesicle axon terminals were also measured.Retinal terminals in MIN were often large (mean size= 2.7 μm2 area) and had a high density of synaptic contacts (0.14 per μm surface area) with conventional dendrites, presynaptic dendrites, and dendritic spines. A high density of F2 presynaptic dendrites (0.08 per μm2 area) was found in MIN. F1 axon terminals were also found frequently (0.04 per μm2). MIN retinal terminals were often organized in glomeruli like those of the dorsal lateral geniculate nucleus.The retinal terminals in VLG were almost always small (mean size= 0.94 μm2 area), although they also had a high density of synaptic contacts (0.17 per μm surface area). They frequently synapsed on small dendrites and dendritic spines and less frequently on large dendrites. Unlike MIN, retinal terminals in VLG rarely contacted F2 presynaptic dendrites which were much less frequent in VLG (0.01 per μm2 area). Like MIN, VLG contained numerous F1 axon terminals (0.06 per μm2 area). No typical retinal glomeruli were found in VLG.These results show that MIN, which contains many Y cells, has a population of large retinal terminals and many F2 presynaptic dendrites. VLG, which apparently has only W cells, contains only small retinal terminals and has fewer F2 presynaptic dendrites. Both have a high density of F1 flat vesicle axon terminals.
Comparative distribution of bombesin/GRP‐ and substance‐P‐like immunoreactivities in rat hypothalamus
Authors: Panula Pertti , Yang Hsiu‐Ying T. , Costa Erminio 
Published: January 2005

AbstractImmunohistochemical localization of bombesin/gastrin‐releasing peptide (GRP)‐like immunoreactivity (BN/GRP‐LI) and substance P‐like immunoreactivity (SP‐LI) in consecutive sections of rat hypothalamus was studied. Bombesin/GRP‐like immunoreactivity in the hypothalamus was partially characterized by gel filtration chromatography followed by radioimmunoassay.In the hypothalamus, SP‐LI was more widely distributed than BN/GRP‐LI. Only the anterior and medial parvocellular parts of the nucleus paraventricularis and the nucleus suprachiasmaticus contained numerous cell bodies which exhibited BN/GRP‐LI. Neurons in these areas did not exhibit SP‐LI. In contrast, cell bodies exhibiting SP‐LI were numerous in the nucleus preopticus medialis and lateralis, nucleus anterior, nucleus ventromedialis and dorsomedialis, nucleus lateralis, nucleus arcuatus, and nucleus premamillaris ventralis and dorsalis. Only occasional cell bodies in these areas exhibited BN/GRP‐LI. It is concluded that the neuronal systems in the hypothalamus containing BN/GRP‐LI and SP‐LI are separate, though the terminal fields in many areas overlap.Two peaks of BN/GRP‐LI were detected after gel filtration chromatography from extracts of the rat nucleus paraventricularis. The high molecular weight form coeluted with synthetic GRP(1‐27), and the small molecular weight form eluted after synthetic bombesin. Thus, the endogenous BN/GRP‐LI is probably not authentic bombesin.
Intracellular marking of physiologically characterized cells in the ventral cochlear nucleus of the cat
Authors: Rouiller E. M. , Ryugo D. K. 
Published: January 2005

AbstractIn the cat ventral cochlear nucleus, separate neuronal classes have been defined based on morphological characteristics; physiologically defined unit types have also been described based on the shape of post‐stimulus‐time‐histograms in response to tone bursts at characteristic frequency. The aim of the present study was to address directly the issue of how morphological cell types relate to physiological unit types. We used intracellular injections of horseradish peroxidase to stain individual neurons after their response characteristics were determined by intracellular recordings. The maintenance of a continuous negative resting potential, the correspondence of the calculated position of the electrode tip at the time of injection to the location of the stained neuron, and the similarity of response properties collected before and after the injection provide evidence that the injected, stained, and recovered neuron corresponds to the functionally defined unit.In the region around the nerve root in the anteroventral cochlear nucleus, two “primarylike” and one “primarylike with notch” units were “bushy” cells. “Bushy” cells are characterized by primary dendrites arising from one hemisphere of the soma and ramifying repeatedly to produce their bushy dendritic arbor. In this same region, the “chopper” and two “on” units were also “bushy” cells. In the posteroventral cochlear nucleus, the “chopper” unit was a “stellate” cell and the “on” unit was an “octopus” cell.These results are partially consistent with previous conclusions based on correlations established between the regional distribution of physiological unit types and morphological cell types. More importantly, they confirm and extend recent intracellular marking data (Rhode et al., ′83b). If our classification schemes have functional significance, we are left with the conclusion that the distinction between “bushy” and “stellate” cells in the auditory nerve root region of the ventral cochlear nucleus does not correspond in any simple way to distinctions between physiological unit types. More than one morphological cell type can exhibit the same particular response pattern, and the same morphological cell type can exhibit several different response patterns.
Development of the cochlear innervation of the dorsal cochlear nucleus of the hamster
Authors: Schweitzer Laura , Cant Nell Beatty 
Published: January 2005

AbstractThe development of cochlear fibers and terminals in the dorsal cochlear nucleus of the hamster was studied with light and electron microscopic techniques. Like the dorsal cochlear nucleus of most other mammals, the dorsal cochlear nucleus of the adult hamster is a laminated structure. Three distinct layers can be identified in cresyl‐violet‐stained sections: the molecular layer, the fusiform cell layer, and the deep layer. The deep layer consists of a superficial zone, free of large cell bodies, and a deep zone which contains the somas of giant cells. Horseradish peroxidase and degeneration studies reveal that the cochlear fibers ramify throughout the deep and fusiform cell layers of the adult hamster but do not enter the molecular layer. In the electron microscope, three types of terminals that contact the fusiform and the giant cells can be distinguished. Only one type of terminal (type LR) degenerates after cochlear ablation and is, therefore, thought to be of cochlear origin. Type LR terminals are found throughout the deep and fusiform cell layers and contact the somas of giant and fusiform cells, as well as their intermingled dendrites in the deep layer.In Golgi‐impregnated material, cochlear fibers are not found in the dorsal cochlear nucleus of the neonatal hamster, although they have entered the ventral cochlear nucleus. Ingrowth of cochlear fibers into the dorsal cochlear nucleus occurs over the first postnatal week and one‐half. A spatial gradient is evident during the ingrowth of the fibers in that they invade the dorsomedial parts of the dorsal cochlear nucleus before they invade the ventrolateral parts. In all parts of the nucleus, the fibers enter the deepest layer and grow progressively more superficially. In the electron microscope, the first appearance of type LR terminals at each depth lags behind the ingrowth of the fibers by about two days.In hamsters, fibers from the basal turns of the cochlea terminate in the dorsomedial dorsal cochlear nucleus, while fibers from the apical turns terminate in the ventrolateral dorsal cochlear nucleus (DCN). The dorsomedial to ventrolateral gradient in the ingrowth of the cochlear fibers into the DCN indicates that the fibers from the basal turn are the first to arrive. Several components of the mammalian cochlea have been shown to mature at the base of the cochlea before they mature at the apex. The present study suggests that maturation gradients in the cochlear nucleus parallel those observed in the cochlea.
On the fate of sympathetic and sensory neurons projecting into a neuroma of the superficial peroneal nerve in the cat
Authors: Jänig W. , McLachlan Elspeth 
Published: January 2005

AbstractCell bodies of sympathetic and sensory axons projecting via the superficial peroneal (SP) nerve supplying hairy skin of the distal hindlimb have been labeled retrogradely with horseradish peroxidase (HRP) on both sides of three cats in which the left SP nerve had been cut and ligated about 5 months previously. Three SP nerves from unoperated cats have also been studied. The location, size, and numbers of labeled somata have been determined from serial sections of lumbosacral dorsal root and sympathetic chain ganglia after standard histochemical processing. The numbers of myelinated fibers in each nerve have also been counted.The segmental distributions of both sympathetic and sensory cell bodies were identical bilaterally in each operated animal, but the number of labeled neurons was reduced on the lesioned side. There were only about 31% of sympathetic and about 51% of sensory somata relative to the numbers on the contralateral side. The average total number of neurons labeled from SP nerves in unoperated animals was about 8% higher than on the control side of operated animals. The average number of myelinated fibers in the neuromatized nerves was not reduced with respect to that in the contralateral nerve and both of these were not significantly different from the number in unoperated animals.The dimensions of samples of labeled sympathetic and sensory somata were reduced on the side with the neuroma, both in comparison with the contralateral side and with unlabeled neurons at the same levels. The mean cross‐sectional area of profiles of sympathetic ganglion cells was 76% of the control; of sensory ganglion cells, 65% of the control.Assuming that HRP labeling was not impaired, we conclude that large numbers of neurons with unmyelinated axons had degenerated in the neuromatized cutaneous nerves.
Immunoreactive leu‐enkephalin in the monkey hypothalamus including observations on its ultrastructural localization in the paraventricular nucleus
Authors: DiFiglia Marian , Aronin Neil 
Published: January 2005

AbstractThe distribution of immunoreactive leu‐enkephalin neurons and fibers in the monkey hypothalamus, including ultrastructural localization in the paraventricular nucleus (PVN), was examined with the peroxidase‐antiperoxidase immunocytochemical method. Immunoreactive leu‐enkephalin cell bodies and fibers were present in the PVN, the region of the dorsal nucleus and nucleus of the anterior commissure, the dorsomedial nucleus, ventro‐medial nucleus, and lateral hypothalamus.Within the PVN labeled cells were found mostly in the medial parvocellular region, and a smaller proportion including some large cells was present in the lateral, and dorsolateral zones. Immunoreactive neurons contained numerous large granular vesicles (LGV) which ranged from 63 to 235 nm in size, suggesting that at least some enkephalin‐containing neurons belong to the population of neurosecretory cells. Positive neurons were postsynaptic to four types of unlabeled axon terminals. Leu‐enkephalin‐containing fibers (some of which were myelinated) and boutons contained small clear vesicles and numerous LGV. Axon terminals made synaptic contacts with the cell bodies, primary and distal dendrites of unlabeled neurons. The findings show that enkephalin‐containing neurons in the PVN integrate a variety of neuronal inputs and provide morphological evidence for the inhibiting influence of enkephalins on the firing rate of PVN neurons. It may be speculated that the effects of opioids on the release of vasopressin and other substances possibly originating from PVN neurons may be regulated in part within the nucleus by locally synapsing axons belonging to enkephalin‐containing neurons.
Counts of axons in electron microscopic sections of ventral roots in lampreys
Authors: Rovainen Carl M. , Dill Dorothy A. 
Published: January 2005

AbstractThe number of motoneurons in the lamprey spinal cord was estimated by counting axons in electron microscopic sections of ventral roots. Physiologically identified and marked motoneurons had one axon each in an ipsilateral ventral root. The corresponding axons in sections were unmyelinated, individually ensheathed, and 2–20 μm in diameter. Lampreys lack an organized sympathetic nervous system, but a minor and variable population of small axons with dense‐cored vesicles was also present in ventral and dorsal roots. The estimated numbers of motor axons per ventral root in adult Ichthyomyzon unicuspis and I. castaneus were 70.6 ± 9.3 (mean ± S.D), in adult landlocked Petromyzon marinus 100.1 ± 15.0, and in large ammocoetes of anadromous Petromyzon marinus 106.8 ± 14.3. The total estimated numbers of myotomal and fin motoneurons were as many as 13,000 in the spinal cord of adult Ichthyomyzon and 24,000 in adult Petromyzon.
Ipsilateral cortical connections from the second and fourth somatic sensory areas in the cat
Authors: Burton H. , Kopf E. M. 
Published: January 2005

AbstractThe ipsilateral corticocortical connections of the second and fourth somatic sensory areas (SII and SIV) were traced with the aid of anterograde or retrograde axonal transport techniques involving horseradish peroxidase conjugated to wheat germ agglutinin (HRP‐WGA) or tritiated amino acids. The injections were placed into physiological defined components of the body representation in SII or SIV. The results from cases with localized injections into SII showed precise topographically organized, reciprocal connections with SI and motor cortex area 4. The distribution of connections in SI included areas 3a, 3b, and 1–2. A uniform pattern of cell and fiber labeling was seen across area 3b and 1 within the zones that were homotypical to the injection site in SII as though only a single representation of the cutaneous surface of the body existed in SI. Intrinsic connections within SII were also topographically arranged. Additional areas found to be interconnected with SII included, in decreasing order of density: area 5, insula, perirhinal cortex (area 36), and ventrolateral orbital cortex. SII connections with area 6 were seen only in the region of the lateral bank of the presylvian sulcus. There may be interconnections between SII and SIV but these were from possible local intrinsic connections in the AEG. The results from injections involving SIV showed reciprocal connections with area 5, the suprasylvian fringe, insula, dorsolateral orbital area, and area 6. The densest connections for SIV were with area 5. No topography was noted in the connections for SIV.
Distribution of 5‐hydroxytryptamine (serotonin) in the brain of the teleost Gasterosteus aculeatus L.
Authors: Ekström Peter , Van Veen Theo 
Published: January 2005

AbstractThe distribution of serotoninergic neurons in the brain of the three‐spined stickleback was demonstrated with the indirect peroxidase‐antiperoxidase (PAP) immunohistochemical method with antibodies against serotonin. Serotoninergic perikarya were demonstrated in the brainstem reticular formation (nucleus raphe dorsalis, nucleus raphe medialis, and nucleus tegmenti dorsalis lateralis) and in the periventricular ventral thalamus and hypothalamus (nucleus ventromedialis thalami, nucleus posterioris periventricularis, nucleus recessus lateralis, and nucleus recessus posterioris). After pharmacological pretreatment of the animals with a monoamine oxidase inhibitor, serotoninergic perikarya were also visualized in area praetectalis and in the medial brainstem, caudal to nucleus raphe medialis. Whereas the cell groups of the brainstem give rise to both ascending and descending pathways, it was not possible to analyze the distribution of efferent projections from the diencephalic cell groups. Distribution of serotoninergic axons showed marked regional differences. Only scattered varicose fibers were demonstrated in the cerebellum, the facial lobes, and the lateral line lobes. In the mesencephalon, the dorsal periventricular tegmentum and the central gray receive only small numbers of serotoninergic axons, while torus semicircularis and the visual layers of tectum opticum are profusely innervated. In the diencephalon, the hypothalamus and ventral thalamus generally display the highest density of serotoninergic axons. Exceptions are found in nucleus glomerulosus and the ventromedial portion of lobus inferioris, where densities are low. In the telencephalon, the density of serotoninergic axons is very high in area dorsalis pars medialis and pars lateralis dorsalis, but low in area dorsalis pars dorsalis and pars lateralis ventralis, and intermediate in area ventralis.
Callosal and intrahemispheric connectivity of the prefrontal association cortex in rhesus monkey: Relation between intraparietal and principal sulcal cortex
Authors: Schwartz Michael L. , Goldman‐Rakic Patricia S. 
Published: January 2005

AbstractHorseradish peroxidase (HRP) histochemistry and double labeling with the fluorescent dyes nuclear yellow (NY) and fast blue (FB) were used to examine and compare the laminar and tangential arrangement of ipsilateral (associational) and contralateral (callosal) neurons and their relative density in three regions of prefrontal granular cortex: Walker's area 46 (principal sulcus), area 8A (superior limb of the arcuate sulcus), and area 11 (lateral orbital sulcus). In all three prefrontal regions, neurons with ipsilateral projections were labeled following injections of tracers into the intraparietal sulcus (IPS) and neurons with callosal projections were sequentially or simultaneously labeled with injections into the contralateral principal sulcus (PS). Quantitative analysis indicates that associational and callosal neurons in prefrontal cortex are distinct cell populations with strikingly similar organization including (1) common topography;(2) common laminar positions in layers III, IV, and V; (3) two‐ to three‐fold higher densities in supragranular than infragranular layers; (4) common morphologies including a high proportion of nonpyramidal soma in the deeper cortical layers; (5) common uneven tangential distribution reminiscent of the interdigitation of their terminal fields; and (6) common subpopulations differing on the basis of terminal arbors. These findings indicate that the posterior parietal cortex and the prefrontal cortex form part of an integrated neural system important for spatiotemporal behaviors.
The Timm‐stained hippocampus of the European hedgehog: A basal mammalian form
Authors: West Mark J. , Gaarskjaer Frank B. , Danscher Gorm 
Published: January 2005

AbstractA quantitative and qualitative description has been made of the components of the Timm‐stained hippocampus of the European hedgehog. While the laminar organization and the relative size of the major subdivisions of the hippocampus (i.e., area dentata, Ammon's horn, and subiculum) are similar to those of the albino laboratory rat, the relative proportions and the staining characteristics of some of the components of the subdivisions are different. The differences are particularly evident in Ammon's horn where regions are poorly differentiated along the dentatosubicular axis and the mossy fiber zone is relatively extensive. The description characterizes a hippocampal form that can be used as a basal reference in comparative studies of the mammalian hippocampus.
Relationship of the vestibular hair cells to magnetic particles in the otolith of the guitarfish sacculus
Authors: Vilches‐Troya J. , Dunn R. F. , O'Leary D. P. 
Published: January 2005

AbstractMagnetite particles were systematically localized within the otolithic mass as a conspicuous curved band in the most ventral region of the guitar‐fish sacculus. The magnetite band overlaid two separated segments of neuroepithelium in the macula, a long segment oriented parallel to the longitudinal body axis, and a short segment oriented in a transverse plane. The exogenous magnetite particles differed from the endogenous otoconia both in their capacity of orienting to magnetic fields, and their difference in mass due to the higher atomic weight of iron. In addition to the normal gravistatic function of the sacculus, two additional receptor functions are hypothesized based upon the differences between the endogenous and exogenous otoconia. A geomagnetic field could induce magnetite displacements detectable by the hair cells for purposes of geomagnetic orientation. Alternatively, the greater atomic weights of magnetite, relative to that of otoconia, could result in gravitational and linear acceleration, which differed in different regions of the macula.