bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution pattern of cell bodies and fibers with neurotensinlike immunoreactivity in the cat hypothalamus
Authors: Hu Haitao , Rao Jayashree K. , Prasad Chandan , Jayaraman A. 
Published: May 2005

AbstractNeurotensin is widely distributed in the central and peripheral nervous systems. Extensive radioimmunoassay and immunohistochemical studies in rats show that the neurotensin immunoreactive perikarya and fibers are most prominent in the hypothalamus. Radioimmunoassay studies have suggested that the levels of neurotensin in the hypothalamus of cats may be six times higher than that of rats. We studied the distribution pattern of neurotensin immunoreactivity within the hypothalamus of the cat by avidinbiotin modification immunohistochemical methods: (1) to define its distribution pattern within the hypothalamus, and (2) to compare our findings with the patterns that have been described in rats. Results show that neurotensin immunoreactive cell bodies and fibers are most prominent in the rostral and intermediate regions of the cat hypothalamus. Cell bodies with neurotensinlike immunoreactivity are seen maximally in the medial preoptic region, the infundibular nucleus, and the lateral hypothalamus. The neurotensin positive fibers are dense in the periventricular regions of the entire rostrocaudal extent of the hypothalamus. This pattern of distribution of neurotensin immunoreactivity is similar to that described in rats. The suprachiasmatic nuclei of the cat hypothalamus, however, contained a significant number of neurotensin immunoreactive cell bodies, an observation not noted in the rat hypothalamus. The neurotensin immunoreactive neurons were more numerous in the lateral hypothalamus than has been reported in rats, but the paraventricular nucleus of the hypothalamus in cats contained fewer neurotensin immunoreactive perikarya. The presence of neurotensin immunoreactive perikarya in the suprachiasmatic nucleus and the apparent increase in the number of neurotensin immunoreactive neurons in the lateral hypothalamus may account for the increased levels of neurotensin reported in cats. Neurotensin has been speculated to play a role in nociception, thermoregulation, and control of arterial pressure by acting as a hormone or a neurotransmitter. Details of the pattern of colocalization of neurotensin with that of other neuropeptides and neurotransmitters will aid in our understanding of its role in these functions.
Quantitative comparisons of gamma‐aminobutyric acid neurons and receptors in the visual cortex of normal and dark‐reared cats
Authors: Mower George D. , Rustad Robin , White W. Frost 
Published: May 2005

AbstractPhysiological studies suggest that the function of the visual cortical gamma‐aminobutyric acid (GABA) system is abnormal in cats reared in total darkness. The present study asked whether visual input is necessary for the normal postnatal anatomical development of the GABA system by comparing GABA neurons and receptors in the visual cortex of normal and dark‐reared cats. Immunohistochemical techniques (anti‐GABA) were used to localize GABA neurons. In both rearing conditions, GABA neurons were stained rather uniformly in all cortical layers. Counts of GABA cells indicated a marked increase in density in dark‐reared compared to normal cats. Counts of total cellular density in cresyl‐stained sections, however, indicated a comparable increase in dark‐reared cats. When corrected for total cellular density, there were no differences between dark‐reared and normal cats in the density of GABA cells per layer, or the relative proportion of GABA cells across cortical layers.In vitro receptor binding of 3H‐muscimol was used to compare GABAA receptors in the two rearing conditions. When corrected for total cellular density, saturation kinetics indicated no difference in the total number or affinity of receptors. Similarly, autoradiographic histology indicated no difference in the laminar distribution of receptors across cortical layers between dark‐reared and normal cats.These results indicate that the postnatal development of GABA neurons and receptors occurs normally in the absence of visual input.
Central projections and trigeminal ganglion location of corneal afferent neurons in the monkey, Macaca fascicularis
Authors: Marfurt Carl F. , Echtenkamp Steven F. 
Published: May 2005

AbstractThe method of transganglionic transport of horseradish peroxidasewheat germ agglutinin conjugate (HRP‐WGA) was used to determine the location within the monkey trigeminal ganglion of the primary afferent neurons that innervate the cornea, and the brainstem and spinal cord termination sites of these cells. In each of four animals, Gelfoam pledgets were saturated with 2% HRP‐WGA in saline and applied to the scratched surface of the central cornea for 30 minutes. Postmortem examination of the corneal whole mounts revealed that the tracer solution remained confined to approximately the central one‐fourth of the cornea with no spread into the peripheral cornea or limbus. Seventy‐two to 96 hours after tracer application, 126–242 labeled cell bodies were observed in the medial region of the ipsilateral trigeminal ganglion. The majority of neurons were concentrated in an area of the ganglion that lay directly caudal to the entering fibers of the ophthalmic nerve, but smaller numbers of cells lay somewhat more laterally, near the region where the ophthalmic and maxillary nerves come together. A very small number of neurons in one animal innervated the cornea by sending their fibers into the maxillary nerve. HRP‐WGA‐labeled terminal fields were present to some extent in all four major rostrocaudal subdivisions of the ipsilateral trigeminal brainstem nuclear complex (TBNC), but the size of the terminal fields and the intensity of labeling differed markedly from one level of the TBNC to the next. Labeled fibers projected heavily to the transitional zone between caudal pars interpolaris and rostral pars caudalis (i.e., the “periobex” region of the TBNC) and moderately to the trigeminal main sensory nucleus, pars oralis, and caudal pars caudalis at the level of the pyramidal decussation. Remaining areas of the TBNC, including rostral pars interpolaris and the midlevel of pars caudalis, received few, if any, corneal afferent projections. Occasional labeled fibers were observed in the dorsal horn of C1 and in the rostral half of C2. It is hoped that data generated in the current investigation of nonhuman primates will contribute to a better understanding of the neural substrates that subserve corneal sensation and the blink reflex in humans.
Long‐spined polymorphic neurons of the medial cortex of lizards: A Golgi, timm, and electron‐microscopic study
Authors: Lopez‐Garcia C. , Martinez‐Guijarro F. J. , Berbel P. , Garcia‐Verdugo J. M. 
Published: May 2005

AbstractThe morphology, ultrastructure, and principal synaptic input of longspined neurons located in the inner plexiform layer of the medial cortex in three related species of lizards is described.Golgi impregnations have been used to define the external morphology of these neurons and their axonal trajectories. Their most striking characteristic is the presence of very long spines or “microdendrites” especially abundant on the distal dendritic segments. Axons have ascendent trajectories, pass through the cell layer, and ramify in the outer plexiform layer. Combined Golgi‐electron microscopy as well as standard electron microscopy permitted the definition of the ultrastructure of these neurons. Timm and sulfide‐osmium methods permitted the detection and characterization of their principal synaptic input (i.e., zinc‐containing boutons).Gamma aminobutyric acid (GABA)‐immunostained sections in one of the species studied allowed the identification of GABA‐immunoreactive somata which had the same morphology and ultrastructure as long‐spined neurons; these GABAwimmunoreactive somata and their processes were found in the same location as long‐spined neurons. This suggests that at least some long‐spined polymorphic neurons are GABA‐ergic and presumably inhibitory.Finally, the neurobiological significance of these long‐spined neurons is discussed and briefly compared with that of similar neurons of the hilus of the fascia dentata of the rat.
Elimination of neurons from the rhesus monkey's lateral geniculate nucleus during development
Authors: Williams Robert W. , Rakic Pasko 
Published: May 2005

AbstractThe timing, magnitude, and spatial distribution of neuron elimination was studied in the dorsal lateral geniculate nucleus of 57 rhesus monkeys (Macaca mulatta) ranging in age from the 48th day of gestation to maturity. Normal and degenerating cells were counted in Nissl‐stained sections by using video‐enhanced differential interference contrast optics and videooverlay microscopy.Before embryonic day 60 (E60), the geniculate nucleus contains 2,200,000 ± 100,000 neurons. Roughly 800,000 of these neurons are eliminated over a 40‐ to 50‐day period spanning the middle third of gestation. Neurons are lost at an average rate of 300 an hour between E48 and E60, and at an average rate of 800 an hour between E60 and E100. Very few neurons are lost after E100, and as early as E103 the population has fallen to the adult average of 1,400,000 ± 90,000. Degenerating neurons are far more common in the magnocellular part of the nucleus than in the parvicellular part. In 20 of 29 cases, the number of neurons is greater on the right than on the left side. The right‐left asymmetry averages about 8.5% and the difference is statistically significant (X2 = 38, p< .001).The period of cell death occurs before the emergence of cell layers in the geniculate nucleus, before the establishment of geniculocortical connections, and before the formation of ocular dominance columns (Rakic, 76). Most important, the depletion of neurons in the geniculate nucleus begins long before the depletion of retinal axons. The number of geniculate neurons is probably a key factor controlling the number of the retinal cells that survive to maturity.
Highly active neuromuscular system in developing lobsters with programmed obsolescence
Authors: Govind C. K. , Kirk Mark D. , Pearce Joanne 
Published: May 2005

AbstractThe primary locomotory apparatus in the three larval stages of the lobster, Homarus americanus, are paddlelike structures on the thoracic appendages called exopodites, which beat almost continuously. Consequently their power and return‐stroke muscles are examples of highly active but short‐lived neuromuscular systems. The muscles, which are well vascularized, are of the fast type with 2‐3‐μm sarcomere lengths and 6 thin filaments surrounding a thick one. The most striking feature, however, is the large volume of mitochondria making up 40‐50% of the fiber. They appear as simple cylinders packed several layers deep along the periphery of the fiber and as large, multibranched forms distributed throughout the fiber and subdividing it into smaller units. The motor innervation to the return‐stroke muscle is via 3 excitatory axons, which generate large junctional potentials and twitch contractions. The muscle is densely populated with large neuromuscular synapses, most of which have a well‐defined active site or dense bar denoting the site of transmitter release. Altogether this motor system is specialized for prolonged activity. Atrophy of the neuromuscular system occurs by the late larval third stage. The muscle fibers lose their identity, fuse, and become vacuolated. The myofibrils condense and erode and the mitochondria are lost. Atrophy of motor innervation is gradual with individual axons dropping out. The largest axon providing most of the innervation is the first to degenerate. Early degenerative changes affect the axon and neuromuscular terminals but not the synaptic contacts, dense bars, and vesicles, which appear intact. Continued atrophy in the postlarval fourth stage reduces the exopodites to vestiges. Thus the returnstroke muscle of the larval exopodites in which muscle fiber and motoneurons are identifiable permits study of the interaction between a neuron and its target muscle undergoing programmed obsolescence.
Peripheral nerve transection induces innervation of embryonic neocortical transplants by specific thalamic fibers in adult mice
Authors: Erzurumlu Reha S. , Ebner Ford F. 
Published: May 2005

AbstractEmbryonic neocortical tissue survives and differentiates when grafted to injured adult neocortex. While these transplants are readily innervated by the host cholinergic fibers, specific thalamic fibers fail to innervate them. The present study was designed to test whether changing the activity levels of the thalamic ventrobasal projection neurons would promote sprouting of their axons into the embryonic cortical implants placed in the barrel field cortex. To achieve this the main input to the these thalamic neurons was eliminated two synapses away, by blocking the peripheral sensory input to the barrel field cortex. Adult hosts underwent unilateral transection of the infraorbital nerve and two days later the contralateral barrel field cortex was lesioned enough to insert an embryonic neocortical graft. Following a one month post‐transplantation period we examined the amount of specific thalamic axon ingrowth into the transplants by injecting the ventrobasal nucleus with horseradish peroxidase. The control cases without prior nerve damage confirmed previous observations that ventrobasal nucleus neurons fail to innervate the implanted neocortex. Transection of the infraorbital nerve prior to transplantation resulted in an unprecedented ingrowth of specific thalamic axons into the transplants. There was no significant difference in the amount of thalamic fiber ingrowth into the transplants when the peripheral nerve was (transection) or was not (cautery) allowed to regenerate. However, transection of the infraorbital nerve permits the nerve to regenerate and at least partially reconnect the sensory periphery, thus leading to the possibility of functional integration of the neocortical transplants into the host trigeminal system.The morphology and distribution of host acetylcholinesterase‐positive fibers that grow into the transplants under both experimental and control conditions were distinctly different from those of thalamic axons. These results provide the first demonstration of peripheral sensory nerve induction of regenerative propensity in specific thalamocortical projection neurons. The thalamic fiber ingrowth should lead to enhanced functional innervation of the neocortical implants and better incorporation of the graft into the adult host brain circuitry.
Neurochemical organization of the hypothalamic projection to the spinal cord in the rat
Authors: Cechetto David F. , Saper Clifford B. 
Published: May 2005

AbstractThe hypothalamus provides a major projection to the spinal cord that innervates primarily lamina I of the dorsal horn and the sympathetic and parasympathetic preganglionic cell columns. We have examined the chemical organization of the neurons that contribute to this pathway by using combined retrograde transport of fluorescent dyes and immunohistochemistry for 15 different putative neurotransmitters or their synthetic enzymes. Our results demonstrate that 5 cytoarchitectonically distinct cell groups in the hypothalamus contribute to the spinal projection and that each has its own predominant chemical types. In the paraventricular nucleus, substantial numbers of hypothalamo‐spinal neurons stain with antisera against arginine vasopressin (25‐35%), oxytocin (20‐25%), and metenkephalin (10%). About 25% of the neurons with spinal projections in the retrochiasmatic area stain with an antiserum against α‐melanocyte‐stimulating hormone. Nearly 100% of the hypothalamo‐spinal neurons in the tuberal lateral hypothalamic area stain with this same antiserum, but these cells do not stain for other proopiomelanocortin‐derived peptides, and so probably contain a cross‐reacting peptide. This population must be distinguished from an adjacent cell group, in the perifornical region, where many spinal projection neurons stain with antisera against dynorphin (25%) or atrial natriuretic peptide (20%). Finally, in the dorsal hypothalamic area as many as 55‐75% of the neurons with spinal projections are dopaminergic, on the basis of their staining with an antiserum against tyrosine hydroxylase.These 5 neurochemically distinct projections from the hypothalamus to the spinal cord are discussed in the context of their possible functional significance.
Visual cortex of the dolphin: An image analysis study
Authors: Morgane Peter J. , Glezer Ilya I. , Jacobs Myron S. 
Published: May 2005

AbstractOn cytoarchitectonic grounds we have identified two distinct types of cortical formations composing the lateral gyrus (visual cortex) of the dolphin and have termed these heterolaminar cortex and homolaminar cortex. The heterolaminar cortex occupies the medial and lateral banks of the entolateral sulcus whereas the homolaminar cortex occupies the remainder of the lateral gyrus both lateral and medial to the entolateral sulcus. Each of these cortices exhibits special cytoarchitectonic features, a major difference being that heterolaminar cortex contains an incipient layer IV whereas layer IV is clearly absent in homolaminar cortex. Quantitative imaging procedures reveal that there is greater laminar differentiation in heterolaminar than in homolaminar cortex. Golgi analysis of neuronal forms and dendritic architecture confirms this distinction between the two types of cortex composing the lateral gyrus. Computer‐assisted morphometric methods have been applied to both types of cortex and indicate by a variety of parameters several quantitative differences in the cellular numbers, types, and organization in each type of cortex. Both types of cortex, homolaminar and heterolaminar, exhibit a markedly higher cellular density in the posterior sector of the lateral gyrus than in the anterior sector. We have also for the first time been able to identify a columnar type of organization of the cetacean visual cortex and have described two types of cytoarchitectonic columns, major and minor, in each of these types of cortex. Comparisons in organization of these basic columnar units between the bat, representing a prototypic brain, and the dolphin reveal many similarities but also major quantitative differences in type of organization between the visual cortices in these species. Marked differences are also seen between the cytoarchitectonic columnar organization of the visual cortices in the dolphin and columnar organization of striate cortex in the human brain, the number of columns per unit of cortex in the human being almost twice that seen in the dolphin brain. Some phylogenetic implications of these findings are discussed in relation to the so‐called „initial”︁ type of cortical organization reconstructed largely by retrospective inference.
Association fiber pathways to the frontal cortex from the superior temporal region in the rhesus monkey
Authors: Petrides M. , Pandya D. N. 
Published: May 2005

AbstractThe projections to the frontal cortex that originate from the various areas of the superior temporal region of the rhesus monkey were investigated with the autoradiographic technique. The results demonstrated that the rostral part of the superior temporal gyrus (areas Pro, Ts1, and Ts2) projects to the proisocortical areas of the orbital and medial frontal cortex, as well as to the nearby orbital areas 13, 12, and 11, and to medial areas 9, 10, and 14. These fibers travel to the frontal lobe as part of the uncinate fascicle. The middle part of the superior temporal gyrus (areas Ts3 and paAlt) projects predominantly to the lateral frontal cortex (areas 12, upper 46, and 9) and to the dorsal aspect of the medial frontal lobe (areas 9 and 10). Only a small number of these fibers terminated within the orbitofrontal cortex. The temporofrontal fibers originating from the middle part of the superior temporal gyrus occupy the lower portion of the extreme capsule and lie just dorsal to the fibers of the uncinate fascicle. The posterior part of the superior temporal gyrus projects to the lateral frontal cortex (area 46, dorsal area 8, and the rostralmost part of dorsal area 6). Some of the fibers from the posterior superior temporal gyrus run initially through the extreme capsule and then cross the claustrum as they ascend to enter the external capsule before continuing their course to the frontal lobe. A larger group of fibers curves round the caudalmost Sylvian fissure and travels to the frontal cortex occupying a position just above and medial to the upper branch of the circular sulcus. This latter pathway constitutes a part of the classically described arcuate fasciculus.
Immunohistochemical localization of gonadotropin‐releasing‐hormone‐associated peptide in the brain of the frog
Authors: Andersen A. C. , Danger J. M. , Fasolo A. , Kah O. , Tonon M. C. , Vaudry H. 
Published: May 2005

AbstractGonadotropin‐releasing‐hormone (GnRH)‐associated peptide (GnRH‐AP) is a 56 amino acid neuropeptide derived from the GnRH prohormone. GnRH‐AP corresponds to the C‐terminal fragment flanking the GnRH peptide. Using an antiserum raised against human GnRH‐AP [1‐56], or against human GnRH, we have investigated the neuronal systems containing either peptide in the central nervous system of the frog Rana ridibunda by immunohistological techniques. A main group of GnRH‐AP‐containing perikarya was found in a dorsoventral orientation of the supra anterior preoptic area (SAPA) just in front of the preoptic recess. Fibers originating from these perikarya projected rostrally toward the medial septal nucleus and the diagonal band of Broca. A network of GnRH‐AP‐immunoreactive (ir) fibers runs caudally from the SAPA toward the ventral hypothalamus. A high density of GnRH‐AP‐ir terminals was found in the median eminence. A few positive fibers were detected in the neural lobe of the pituitary, particularly in the region bordering the pars intermedia. Labelling of consecutive sections by either GnRH‐AP or GnRH antibodies showed that GnRH and GnRH‐AP‐like irs were contained in the same cells of the SAPA. The double‐staining technique with electrophoretic elution confirmed the colocalization of GnRH and GnRH‐AP within the same neurons. Such a coexistence indicates that frog GnRH originates from a high molecular weight precursor which is closely related to rat pro‐GnRH. The relative preservation of the C‐terminal sequence of the pro‐GnRH during evolution suggests that GnRH‐AP may possess intrinsic biological activity. The high density of GnRH‐AP‐containing neurons projecting through the external zone of the median eminence would support the concept that GnRH‐AP is involved in the modulation of pituitary hormone secretion.