bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early differentiation of ganglion, amacrine, bipolar, and muller cells in the developing fovea of human retina
Authors: van Driel Diana , Provis Jan M. , Billson Francis A. 
Published: May 2005

AbstractWe examined the differntiation and maturation of neurons and glia of the inner nuclear layer (INL) and ganglion cell layer (GCL) in the retina of a human fetus of 15 weeks gestation. Serial, ultrathin sections were cut from a resinembedded specimen from the posterior pole of the retina. The region of the putative fovea was defined by the absence of rod photoreceptors from the outer nuclear layer; only sections through the putative fovea were studied. Cell somata were classified on the basis of morphological criteria and, through the analysis of serial sections, morphological characteristics of the cell processes were established. In the inner plexiform layer (IPL), the types of synapses were analysed. The majority of cells in the INL and GCL were differentiated and could be identified. Ganglion cell somata were observed in the GCL and INL. Of 186 somata analysed in the INL, 66 were Muller cells, 21 amacrine cells, and 2 ganglion cells; a further 7 cells were classified as either amacrine or ganglion. Bipolar cells were thought to comprise the majority of the remaining 90 somata, but these could not be positively identified, as it was not possible to trace bipolar cell axons to their cell bodies deep in the INL. A detailed description of the morphological characteristics of the identified cells and their processes, and of the axonal processes of bipolar cells, is provided. Puncta adherentia and other simple intercellular junctions were commonly seen in the IPL and involved all cell types. Amacrine cell synapses and immature, monad bipolar cell synapses were common within the IPL. Dyad bipolar synapses were uncommon at this stage of development. A possible sequence of synaptogenesis in the IPL is discussed.
Inhibin β, somatostatin, and enkephalin immunoreactivities coexist in caudal medullary neurons that project to the paraventricular nucleus of the hypothalamus
Authors: Sawchenko P. E. , Arias C. , Bittencourt J. C. 
Published: May 2005

AbstractConcurrent and sequential dual immunohistochemical labeling methods were used in combination, along with retrograde tracing techniques, to determine the extent to which inhibin < (Iβ), somatostatin‐28 (SS‐28), and enkephalin (ENK) immunoreactivity (IR) might be jointly expressed in neurons centered in the caudal part of the nucleus of the solitary tract )NTS( that project to the paraventricular nucleus of the hypothalamus (PVH). The results indicate that at least 65% of Iβ‐stained neurons in the NTS also express SS‐28 IR, and at least 33% are ENK‐positive. At least 25% of the Iβ IR population stains positively for all three peptides. A substantial number of cells stained with markers for two, or all three, peptide families, could be retrogradely labeled following tracer deposits centered in the PVH. Prominent Iβ and SS‐28 IR projections from the caudal medulla to the hypothalamus have been described and include a preferential input to oxytocinergic (OT) compartments of the magnocellular neurosecretory system. The present results suggest that these arise in large measure from a common pool of neurons, a subset of which also shows ENK IR. Implications for the control of OT secretion, and for the processing of sensory information through the NTS, are discussed.
Tyrosine hydroxylase‐like immunoreactivity in the brain of fifth instar Rhodnius prolixus stål (hemiptera: Reduviidae)
Authors: Nyhof‐Young Joyce , Orchard Ian 
Published: May 2005

AbstractThe distribution of tyrosine hydroxylase‐like immunoreactivity was mapped in whole‐mount preparations of the brain of fifth instar Rhodnius prolixus Stål. Immunoreactivity was limited to neuronal cell bodies and processes, which were distributed over both ventral and dorsal surfaces of the CNS. The brain, excluding the optic lobes, contained about 160 tyrosine hydroxylase‐like immunoreactive cells. Each optic lobe contained two groups of small round cell bodies, which were too numerous to count. The wide distribution of immunoreactivity suggests that tyrosine hydroxylase is present in neurons with diverse central functions. Tyrosine hydroxylase is the rate‐limiting enzyme in catecholamine synthesis in vertebrates. A comparison of a map of the distribution of catecholamine‐induced fluorescence obtained using the glyoxylic‐acid technique (Flanagan; J. Insect Physiol. 30(9):697‐704, 1984) with that generated for tyrosine hydroxylase reveals considerable overlap between the two systems, suggesting that tyrosine hydroxylase is used in the catecholamine pathway in this insect. The mapping of these reactive neurons is an important step for identification of unique tyrosine hydroxylase‐containing neurons, and is our initial step in the analysis of identified catecholamine‐containing neurons in R. prolixus.
Contribution of brainstem GABAergic circuitry to descending antinociceptive controls: I. GABA‐immunoreactive projection neurons in the periaqueductal gray and nucleus raphe magnus
Authors: Reichling David B. , Basbaum Allan I. 
Published: May 2005

AbstractThe fact that GABA receptor agonists and antagonists influence nociceptive thresholds when microinjected into the rostroventral medulla or in the spinal cord may reflect the involvement of GABAergic neuronal elements in endogenous antinociceptive pathways. In the present study we used immunocytochemistry and retrograde tract tracing to investigate the contribution of GABAergic projection neurons to the antinociceptive network linking the midbrain periaqueductal gray matter (PAG), the nucleus raphe magnus (NRM), and the spinal cord dorsal horn. The tracer, WGAapoHRP‐Au was injected into either the NRM or the spinal cord and the distribution of labeled neurons in sections of the PAG and medulla, respectively, was studied. The same sections were immunostained to demonstrate GABA‐immunoreactive neurons. Although GABA‐immunoreactive neurons were abundant in the PAG, only 1.5% were retrogradely labeled from the NRM. Similarly, very few GABA‐immunoreactive neurons within the cytoarchitectural boundaries of the NRM were retrogradely labeled from the spinal cord. A much higher proportion of GABA‐immunoreactive neurons in the region lateral to the NRM, however, were retrogradely labeled from the spinal cord. Eighteen percent of GABA‐immunoreactive neurons were retrogradely labeled in the nucleus reticularis paragigantocellularis; conversely, 15% of the retrogradely labeled neurons in this region were GABA‐immunoreactive. These results indicate that GABAergic projections constitute a very minor component of the PAG‐NRM‐spinal cord pathway; however, there is a significant contribution of GABAergic neurons to the spinal projections that originate lateral to the NRM. The majority of GABAergic neurons in the PAG and NRM are presumed to be inhibitory interneurons that directly or indirectly regulate activity in efferent pathways from these regions.
Generation patterns of immunocytochemically identified cholinergic neurons at autonomic levels of the rat spinal cord
Authors: Barber Robert P. , Phelps Patricia E. , Vaughn James E. 
Published: May 2005

AbstractThe time at which a neuron is “born” appears to have significant consequences for the cell's subsequent differentiation. As part of a continuing investigation of cholinergic neuronal development, we have combined ChAT immunocytochemistry and [3H]thymidine autoradiography to determine the generation patterns of somatic and autonomic motor neurons at upper thoracic (T1‐3), upper lumbar (L1‐3), and lumbosacral (L6‐S1) levels of the rat spinal cord. Additionally, the generation patterns of two subsets of cholinergic interneurons (partition cells and central canal cluster cells) were compared with those of somatic and autonomic motor neurons. Embryonic day 11 (E11) was the first day of cholinergic neuronal generation at each of the three spinal levels studied, and it also was the peak generation day for somatic and autonomic neurons in the upper thoracic spinal cord. The peak generation of homologous neurons at upper lumbar and lumbosacral spinal levels occurred at E12 and E13, respectively. Somatic and autonomic motor neurons were generated synchronously, and their production at each rostrocaudal level was virtually completed within a 2‐day period. Cholinergic interneurons were generated 1 or 2 days later than motor neurons at the same rostrocaudal level. In summary, the birthdays of all spinal cholinergic neurons studied followed the general rostrocaudal spatiotemporal gradient of spinal neurogenesis. In addition, the generation of cholinergic interneurons also followed the general ventrodorsal gradient. In contrast, however, autonomic motor neurons disobeyed the rule of a ventral‐to‐dorsal progression of spinal neuronal generation, thus adding another example in which autonomic motor neurons display unusual developmental patterns.
The size and dendritic structure of HRP‐labeled gamma motoneurons in the cat spinal cord
Authors: Moschovakis A. K. , Burke R. E. , Fyffe R. E. W. 
Published: May 2005

AbstractWe report quantitative data obtained from 60 fully reconstructed dendritic trees belonging to eight γ‐motoneurons (γ‐MNs) and six additional γ‐MNs that were not completely reconstructed. The cells were labeled intracellularly with horseradish peroxidase (HRP). These data are compared to measurements from 79 reconstructed dendrites belonging to seven documented α‐motoneurons (α‐MNs), supplemented by a larger sample of α‐MNs labeled intracellularly or by retrograde transport with HRP. As expected from earlier studies, the soma dimensions and total membrane area of γ‐MNs were smaller than those of α‐MNs. Although γ‐MN dendrites were, on average, slightly but significantly longer than those of α‐MNs, the former had, on average, smaller diameter stem dendrites, less membrane area, and less profuse branching, and they tended to branch closer to the soma and to terminate farther from the soma. These differences were evident even when subsets of dendrites with similar stem diameters were compared. Some of the anatomical distinctions suggest that γ‐MNs are qualitatively as well as quantitatively different from α‐MNs, even though the distributions of many of the morphological variables examined showed no abrupt discontinuities between the two motoneuron groups.
Ascending general visceral pathways within the brainstems of two teleost fishes: Ictalurus punctatus and Carassius auratus
Authors: Finger Thomas E. , Kanwal Jagmeet S. 
Published: May 2005

AbstractThe primary general visceral nucleus in goldfish. (Carassius auratus) and catfish (Ictalurus punctatus) is located at the ventroposterior boundary of the vagal gustatory lobe and receives coelomic visceral, but not gustatory inputs. The neuronal tracer horseradish peroxidase (HRP) was employed to visualize sources of input to and/ascending projections from the primary general visceral nucleus in these species. In addition, immunocytochemical techniques were utilized to define the cytological divisions within the pontine gustatory‐visceral complex. The pontine secondary visceral nuclei in both catfish and goldfish contains numerous somata and fibers immunoreactive for calcitonin gene‐related peptide (CGRP). In contrast, the secondary gustatory nuclei are devoid of fibers and cells immunoreactive for CGRP.In both the goldfish and the channel catfish, the primary general visceral nucleus receives input from the vagal gustatory lobe, as well as the medullary reticular formation. In the channel catfish, the primary general visceral nucleus projects bilaterally to the secondary visceral nucleus, which lies rostrolateral to the secondary gustatory nucleus in the dorsal pons. Fibers cross the midline via the rostral part of the isthmic commissure. Injection of HRP into the primary general visceral nucleus of a goldfish labels ascending fibers that project to a secondary visceral nucleus situated ventral, lateral, and rostral to the secondary gustatory complex. In general, the results indicate that general visceral systems ascend in parallel to gustatory systems within the brainstem, and that general visceral but not gustatory nuclei are immunoreactive for the peptide CGRP.
Selective vulnerability of the hippocampal pyramidal neurons to hypothyroidism in male and female rats
Authors: Madeira M. D. , Sousa N. , Lima‐Andrade M. T. , Calheiros F. , Cadete‐Leite A. , Paula‐Barbosa M. M. 
Published: May 2005

AbstractThyroid hormone deficiency has long been considered to affect profoundly such cognitive functions as learning and memory, which are known to depend on the structural integrity of the hippocampal formation. Since we previously found that the number of granule cells of the dentate gyrus is reduced in hypothyroid animals, we decided to extend our observations to the pyramidal cells of the hippocampus in order to gain further insight into the effects of hypothyroidism upon the other neuronal links of the hippocampal trisynaptic circuitry, inasmuch as CA1 neurons are known to be particularly vulnerable to aggressive agents.Groups of 6 male and 6 female rats aged 30 and 180 days were analysed separately after being treated as follows: (1) hypothyroid from day 0 until day 30 (30‐day‐old hypothyroid group); (2) respective 30‐day‐old control; (3) hypothyroid from day 0 until day 180 (180‐day‐old hypothyroid group); (4) hypothyroid until day 30 and thenceforth maintained euthyroid (recovery group); (5) hypothyroid since day 30 (adult hypothyroid group); and (6) respective 180‐day‐old control. The volume of the pyramidal cell layer of the CA1 and CA3 regions and the numerical density of the respective neurons were evaluated, thereby allowing us to estimate the total number of pyramidal cells in each hippocampal region. The areal density and the mean nuclear volume of CA1 and CA3 pyramidal cells were also estimated.In the CA3 region, we found that hypothyroidism, whatever its duration and time of onset, induces a reduction in the volume of the pyramidal cell layer and a parallel increase in the numerical density of its neurons, without interfering with the total number of pyramidal cells. Conversely, in the CA1 region, thyroid hormone deficiency started either neonatally or during maturity was found to lead to a decrease in the total number of pyramidal cells. Reductions ranging between 14.2 and 22.5% were found in 30 and 180‐day‐old hypothyroid groups. The reestablishment of a euthyroid state did not ameliorate the referred neuronal loss.The present results support the view that hypothyroidism induces small alterations in the structural organization of the hippocampal CA3 region, contrary to what happens in CA1 in which neuronal death occurs. Furthermore, the data presented herein demonstrate that the total number of CA1 pyramidal cells displays sexual dimorphism that is not affected by thyroid hormone manipulations. These findings allow us to admit that hypothyroidism induces anatomical changes in the hippocampus which are in line with those reported for the dentate gyrus, thereby providing additional morphological basis for the cognitive alterations described in this condition. © 1992 Wiley‐Liss, Inc.
Vasopressin innervation of sexually dimorphic structures of the gerbil forebrain under various hormonal conditions
Authors: Crenshaw Bradley J. , de Vries Geert J. , Yahr Pauline 
Published: May 2005

AbstractThe distribution of vasopressin‐immunoreactive fibers in the forebrain of male and female gerbils was studied, focusing on the lateral septum and the sexually dimorphic area (SDA) found at the border between the medial preoptic area and the anterior hypothalamus. To study hormonal influences on the densities of these fibers, some animals of each sex were gonadectomized or gonadectomized and given testosterone. Others were given sham operations. High densities of vasopressin‐immunoreactive fibers were found in the lateral septum. In the SDA, the densities of these fibers varied considerably. Many were found in the medial half of the medial SDA, but few in the lateral SDA. Vasopressin‐immunoreactive fibers were also sparse in the lateral half of the medial SDA, except for a dense cluster in the SDA pars compacta of males. Similar but smaller clusters were seen in the same location in females although the SDA pars compacta could not be detected in Nissl‐stained sections from the female brains. Fiber densities in two areas, the lateral septum and the lateral SDA, were sensitive to gonadal steroids. In both cases, castration reduced fiber density and testosterone enhanced it. In addition, fiber densities in two areas, the lateral septum and the medial SDA, were sexually dimorphic. In each case, fiber density was greater in males. There was no hormonal effect, however, on the fiber densities in the medial SDA. The fact that the fiber plexuses in the lateral septum and the medial SDA respond differently to gonadal steroids suggests that they arise from different cells and possibly from different areas of the brain. The vasopressin‐immunoreactive fibers in the lateral septum probably come from steroid‐sensitive vasopressin neurons in the bed nucleus of the stria terminalis. Those in the medial SDA may originate in the dorsal aspect of the suprachiasmatic nucleus where vasopressin‐immunoreactive cell bodies were seen. © 1992 Wiley‐Liss, Inc.
Localization of 3H‐nicotine, 125I‐kappa‐bungarotoxin, and 125I‐alpha‐bungarotoxin binding to nicotinic sites in the chicken forebrain and midbrain
Authors: Sorenson Eva M. , Chiappinelli Vincent A. 
Published: May 2005

AbstractWe have previously localized cholinergic cell bodies and fibers within the midbrain of the chicken with choline acetyltransferase immunohistochemistry. In a continuing effort to characterize the central cholinergic system, the present study examines the distribution of various nicotinic acetylcholine receptors in the forebrain and midbrain of the chicken. The binding of 3H‐nicotine, 125I‐kappa‐bungarotoxin, and 125I‐α‐bungarotoxin was localized by film autoradiography in adjacent sections of the adult chicken brain, allowing a comparison of the distribution of different classes of nicotinic binding sites within the brain.Although all three ligands were often co‐localized, there were areas that bound 3H‐nicotine but not the 125I‐neurotoxins, or vice versa. Very high densities of all three ligands were found in the hyperstriatum ventrale; the nucleus geniculatus lateralis, pars ventralis; the griseum tectale; the nucleus dorsolateralis anterior thalami; the nucleus lentiformis mesencephali, pars lateralis and pars medialis; the periventricular organ; and the stratum griseum et fibrosum superficial, layer f of the optic tectum. The nucleus spiriformis lateralis had the highest levels of 3H‐nicotine binding in the chicken brain, but it did not bind either of the two snake neurotoxins. On the other hand, high levels of both 125I‐α‐bungarotoxin and 125I‐kappa‐bungarotoxin binding were found in the nucleus semilunaris and the nucleus ovoidalis, but these areas contained little or no 3H‐nicotine binding. No unique 125I‐kappa‐bungarotoxin sites, unrecognized by 125I‐α‐bungarotoxin, were identified by the low resolution autoradiography performed in this study.In general, nicotinic receptors were found in areas that have been reported to contain cholinergic cell bodies or fibers. Comparison of our results with the expression of neuronal nicotinic receptor subunits, as determined by in situ hybridization, suggests that many of the high affinity 3H‐nicotine sites are localized presynaptically, as, for example, in the retinorecipient nuclei and the nucleus interpeduncularis. The lack of 125I‐kappa‐bungarotoxin binding in the presence of α‐bungarotoxin indicates that the chicken brain has only very low levels of a unique kappa‐bungarotoxin site. This is in marked contrast to chicken, frog, and rat autonomic ganglia, where a unique kappa‐neurotoxin‐sensitive receptor has been identified and shown to mediate nicotinic neurotransmission. © 1992 Wiley‐Liss, Inc.
Distribution of corticotropin‐releasing factor‐like immunoreactivity in squirrel monkey (Saimiri sciureus) amygdala
Authors: Bassett J. L. , Foote S. L. 
Published: May 2005

AbstractPrevious anatomical studies of corticotropin‐releasing factor (CRF)‐like immunoreactivity in rat brain have reported prominent clustering of neuronal elements containing this peptide within the amygdala. The highest concentrations of both CRF‐positive cells and fibers were evident in the central nucleus, an observation consistent with the putative role of this peptide in autonomic and endocrine regulation. In addition, lower densities of CRF‐positive somata and processes have boon noted in other amygdaloid nuclei. However, the distribution of CRF‐like immunoreactivity in the amygdala has not been described for any primate species. Such a description would be of interest since substantial differences in the distribution of CRF in rodent and primate have been reported for other brain regions.The present study uses immunohistochemical methods, with a polyclonal antiserum directed against the human form of CRF, to determine the distribution of this peptide in non‐colchicine‐treated monkeys (Saimiri sciureus). Within the amygdaloid complex, the most numerous and concentrated collections of CRF‐positive neurons were seen in the basal and lateral nuclei. The highest densities of CRF‐positive fibers and terminals were seen in the lateral and central amygdaloid nuclei. Moderately dense plexuses of CRF‐positive fibers also were seen in layer Ia of the periamygdaloid cortex, nucleus of the lateral olfactory tract, anterior and posterior cortical nuclei, and the medial nucleus. Thus, the distribution of CRF‐like immunoreactivity differs substantially in monkey and rat amygdala. Since CRF‐positive perikarya in monkey are most prominent in nuclei with pronounced interconnections with neocortex, these differences may be an integral component of the increased cortical development that characterizes the primate brain. © 1992 Wiley‐Liss, Inc.