bluuebunny/crossref_metadata_2025_split huggingface dataset:
Retinotopic organization of central optic projections in Rana pipiens
Authors: Montgomery Neil , Fite Katherine V. 
Published: January 2005

AbstractThe retinotopic organization of the anuran visual system has been investigated with the method of selective anterograde transport of horseradish peroxidase (HRP) following retinal lesions. The course of optic axons to specific structures was also confirmed by retrograde transport in the optic tract following HRP injections in the tectum and pretectum. As the optic nerve reaches the optic chiasm, the fibers from each of the four retinal quadrants appear as bands with the nasal (n) quadrant entering the chiasmal anterior pole, followed by ventral (v), temporal (t), and dorsal (d) quadrants. The preoptic nucleus is the first structure to be innervated, followed by the suprachiasmatic nucleus; both are innervated directly from fibers in the dorsal part of the optic nerve, which contains fibers from all the retinal quadrants. Each quadrant expands across the dorsoventral extent of the chiasm at the point where it enters. At this level the quadrants are arrayed along the rostrocaudal axis (as they are later in the marginal optic tract) in the sequence n‐v‐t‐d. Optic fibers then spread across the chiasm, the nasal quadrant splits, taking up positions in the rostral and caudal margins of the optic radiation. Following the split in the nasal representation, the optic tract is transformed into topographically arranged sheets in the marginal optic tract.In the other retinorecipient nuclei, the sheet of optic axons is transformed back into the shape of the retinal hemisphere. Topographic maps of this kind display one of two possible orientations: (1) in the tectum and the nucleus lentiformis mesencephali (nLM), the temporal retina is represented in the anterior portion of the nucleus, whereas the nasal quadrant is found in the posterior portion; (2) in the thalamus, the retinotopic map is organized as a mirror‐image reversal of that seen in the tectum and nLM (i.e., the nasal pole is anterior, whereas the temporal pole is in the posterior portion of the nucleus). Structures with this type of retinal map include the rostral visual nucleus, the corpus geniculatum, the nucleus of Bellonci, and the posterior thalamic nucleus. A third type of innervation occurs in the nucleus of the basal optic root (nBOR), which is the only mesencephalic visual nucleus not innervated by the marginal optic tract. The basal optic root is formed by the fibers exiting most caudally from the optic chiasm. All the retinal quadrants contribute to the basal optic root, but no evidence of retinotopy was found in nBOR.Following HRP injections in the pretectum, the majority of retrogradely labelled fibers were found in the medial portions of the marginal optic tract and chiasm. Tectal injections labelled fibers primarily in the lateral portions of the marginal optic tract and chiasm. It is proposed that this difference is related to the sequential, ontogenetic development of the retina and its central target nuclei.
Ultrastructural analysis of gaba‐immunoreactive elements in the monkey thalamic ventrobasal complex
Authors: Ohara P. T. , Chazal G. , Ralston H. J. 
Published: January 2005

AbstractThis study describes the ventrobasal complex of the primate by using GABA immunocytochemistry at the electron microscopic level. The primate ventrobasal complex has a similar synaptic organization to sensory thalamic nuclei in other species. Two synaptic profiles within the ventrobasal complex contain flattened or pleomorphic synaptic vesicles and are GABA‐immunoreactive. F‐boutons (=F1 type, Guillery's classification; Guillery: Z. Zellforsch. 96: 1–38, '69) are located principally in the extraglomerular neuropil and contain densely packed flattened synaptic vesicles and several elongate mitochondria and establish symmetric (Gray's type II) synaptic contacts. These boutons are not found postsynaptic to any other element and are presynaptic principally to nonimmunoreactive elements that are thought to be thalamocortical relay cell dendrites. PSD‐boutons (=F2 type, Guillery's classification) contain a moderate number of flattened or pleomorphic synaptic vesicles and fewer mitochondria than F‐boutons. PSD‐boutons are found in glomerular and extraglomerular areas of neuropil and establish symmetric synaptic contacts. These boutons are considered to be appendages of interneuron dendrites and are postsynaptic to RL‐, RS (Guillery's classification)‐, F‐, and other PSD‐boutons. PSD‐boutons are presynaptic to thalamocortical relay neurons and interneuron dendrites including PSD‐boutons. Problems in distinguishing F‐ from PSD‐boutons are addressed by comparing immunostained and nonimmunostained material and by the use of serial sections. The majority of synaptic contacts between pleomorphic vesicle‐containing profiles appear to be between PSD‐boutons and other components of interneurons. Few contacts between F‐boutons and local circuit neurons are seen. These data suggest the principal GABAergic input to interneurons in the primate ventrobasal complex is derived from other interneurons.
Lumbar dorsal root ganglia of the cat: A quantitative study of peptide immunoreactivity and cell size
Authors: Garry M. G. , Miller K. E. , Seybold V. S. 
Published: January 2005

AbstractThe purpose of the present study was to quantify the extent to which several peptides and serotonin coexist with substance P or somatostatin in selected lumbar dorsal root ganglia of the cat. The technique for the simultaneous visualization of two antigens by immunofluorescence was used to investigate the coexistence of neuropeptides in the lumbar dorsal root ganglia of colchicine‐treated cats. Perikarya immunoreactive for calcitonin gene‐related peptide, galanin, leu‐enkephalin, somatostatin, and substance P were visualized in both the lumbar 5 and 6 dorsal root ganglia. In contrast, no immunoreactivity was observed for adipokinetic hormone, bombesin, dynorphin A, met‐enkephalin, oxytocin, tyrosine hydroxylase, thyrotropin‐releasing hormone, vasopressin, vasoactive intestinal peptide, or serotonin in either ganglion examined. Substance P coexisted with calcitonin‐gene‐related peptide, somatostatin, and leu‐enkephalin. Somatostatin was colocalized with calcitonin gene‐related peptide, leu‐enkephalin, and substance P but coexisted with galanin minimally. The cell area of immunoreactive perikarya was also examined. Data concerning the cross‐sectional area of immunoreactive cells indicated that somatostatin‐immunoreactive perikarya were generally the largest population observed (up to ∼6,000 μm2). Somatostatin and calcitonin gene‐related peptide, as well as substance P and calcitonin gene‐related peptide, coexisted in populations of cell bodies that had a smaller size (less than 2,000 μm2). These results suggest that certain peptides which coexist in the dorsal root ganglia may provide histochemical markers for functional groups of primary afferent neurons.
Organization of lateral geniculate‐hypothalamic connections in the rat
Authors: Card J. Patrick , Moore Robert Y. 
Published: January 2005

AbstractThe location and chemical identity of neurons interconnecting the lateral geniculate complex and the hypothalamus were analyzed in order to provide further information on the anatomical substrates for the entrainment of circadian rhythms. A particular objective of the study was to characterize the neurons projecting between the intergeniculate leaflet (IGL) of the lateral geniculate complex and the suprachiasmatic nucleus (SCN) and related anterior hypothalamic areas. The connectivity experiments employed five combinations of fluorescent tracer injection and were combined with immunohistochemical localization of either neuropeptide Y (NPY), met‐enkephalin (mENK) or the vasoactive intestinal polypeptide (VIP)/peptide histidine isoleucine (PHI) group. IGL efferents. Injection of tracer into the SCN results in retrograde labeling of NPY‐immunoreactive neurons in the IGL as would be expected from prior work. These neurons and their terminals also contain the C‐flanking peptide of the NPY precursor molecule (CPON). In addition, there are two additional groups of neurons in the IGL that project either to the SCN or the contralateral IGL but do not exhibit NPY immunoreactivity. These include a substantial population of cells that project to the SCN and an even larger group of neurons which project to the contralateral IGL and contain mENK immunoreactivity. Hypothalamic efferents. Injection of tracer into the IGL results in retrograde labeling of scattered neurons throughout the SCN and immediately adjacent anterior hypothalamus ipsilaterally and also in labeling of a small number of neurons in the same areas on the contralateral side of the brain. In rare instances, individual SCN neurons appear to project to both IGLs. However, the retrochiasmatic area (RCA) contains the largest number of retrogradely labeled neurons following tracer injections into the IGL. These neurons are concentrated along the midsagittal plane and in the lateral RCA ipsilateral to the injected IGL. None of the labeled neurons in the SCN or adjacent anterior hypothalamus exhibit VIP or PHI immunoreactivity.These observations indicate that the anatomical relations between the geniculate complex and the anterior hypothalamus are more complex than previously shown. First, the geniculohypothalamic tract arises from two distinct groups of IGL neurons: one contains NPY/CPON immunoreactivity; the chemical content of the other is not characterized at the present time. Second, the commissural projection between the two IGLs is formed by a third group of neurons, and these cells contain mENK immunoreactivity. Finally, reciprocal projections from the hypothalamus to the IGL arise from neurons in the retrochiasmatic area, SCN, and adjacent anterior hypothalamus. These anatomical observations demonstrate that the neuronal circuitry involved in the entrainment of circadian rhythms consists of a complex series of projections that interconnect the SCN, anterior hypothalamus, and IGL.
Distribution of somatostatin‐like immunoreactivity in the monkey amygdala
Authors: Amaral David G. , Avendañto Carlos , Benoit Robert 
Published: January 2005

AbstractThe distribution of somatostatin‐like immunoreactivity was studied in the macaque monkey (Macaca fascicularis) by using primary antisera that recognize somatostatin‐28 (S309) or somatostatin‐281‐12 (S320). Somatostatin‐immunoreactive neuronal cell bodies were observed in all amygdaloid nuclei and cortical regions. The density of labeled cells varied substantially, however, both within and across the various amygdaloid subdivisions. The highest densities of labeled neurons were observed in layer III of the periamygdaloid cortex, in layers II and III of the medial nucleus, in the magnocellular division of the accessory basal nucleus, and in the medial portion of the lateral nucleus. Many labeled cells were also consistently observed in the caudoventral portion of the lateral division of the central nucleus. Labeled cells were heterogeneous in size and shape ranging from small and spherical to large and multipolar. The density of somatostatin‐immunoreactive fibers also varied greatly from region to region and was often inversely related to the density of immunoreactive cells. Highest densities of immunoreactive fibers were observed in the periamygdaloid cortex, medial nucleus, parvicellular division of the accessory basal nucleus, paralaminar nucleus, ventrolateral portion of the lateral nucleus, parvicellular division of the basal nucleus, and the lateral division of the central nucleus. Fibers and terminals in the central nucleus had a coarsely varicose appearance and this pattern of staining was continuous along the trajectory of the central nucleus projection to the bed nucleus of the stria terminalis. The large, immunoreactive varicosities located in this area often appeared to outline dendritic or vascular profiles within the substantia innominata. The lowest levels of somatostatin‐immunoreactive fibers were observed in the magnocellular division of the basal nucleus and in the ventromedial portion of the accessory basal nucleus.
Distribution of alpha2, alpha3, alpha4, and beta2 neuronal nicotinic receptor subunit mRNAs in the central nervous system: A hybridization histochemical study in the rat
Authors: Wada Etsuko , Wada Keiji , Boulter Jim , Deneris Evan , Heinemann Steve , Patrick Jim , Swanson Larry W. 
Published: January 2005

AbstractPrevious studies have revealed the existence of a gene family that encodes a group of neuronal nicotinic acetylcholine receptor (nAChR) subunits. Four members of this family have been characterized thus far; three of these subunits (alpha2, alpha3, and alpha4) are structurally related to the ligand binding subunit expressed in muscle and form functional nAChRs when combined with the beta2 gene product in Xenopus oocytes. In addition, the alpha4 gene appears to encode two different products (alpha4‐1 and alpha4‐2) that have been proposed to arise by alternative mRNA splicing. Nine different [35S]‐complementary ribonucleic acid (cRNA) probes were used in the present study to map the distribution of these nAChR subunit mRNAs throughout the central nervous system (CNS) of the rat.It was found that the beta2 gene is expressed in most regions of the CNS, as are the alpha subunit genes as a group. However, each alpha gene is expressed in a unique, although partly overlapping, set of neuronal structures. Alpha4 is the most widely expressed alpha gene, and the evidence suggests that mRNAs for the alpha4‐1 and alpha4‐2 products are virtually always found in the same regions, in approximately the same ratios (alpha4‐2 greater than alpha4‐1). In addition, there are several examples of cell groups that express beta2 but none of the alpha subunit mRNAs examined here (particularly in the hypothalamus), as well as all groups that express the converse, thus suggesting that additional neuronal nAChR subunits remain to be characterized. Finally, the extensive expression of multiple alpha subunits in certain regions, particularly for alpha3 and alpha4 in the thalamus, suggests that there is microheterogeneity in a small population of cells or that some neurons may express more than one alpha subunit. This problem needs to be examined directly with double labeling methods but raises the possibility that some neuronal nAChRs may be composed of more than one kind of alpha subunit. The wide expression of these receptor genes suggests that nAChRs constitute major excitatory systems in the CNS.
“Necklace olfactory glomeruli” form unique components of the rat primary olfactory system
Authors: Shinoda Koh , Shiotani Yahe , Osawa Yoshio 
Published: January 2005

AbstractA distinct subset of rat primary olfactory neurons was identified immunohistochemically by means of a polyclonal antibody against human placental antigen X‐P2 (hPAX‐P2), an incompletely characterized substance found in all estrogen‐biosynthetic organs. The subset of olfactory receptor cells was distributed widely over the olfactory epithelium with some degree of concentration on the dorsocaudal walls of nasal subcavities. The subset formed unique “necklace olfactory glomeruli,” which were composed of seven to nine solitary glomeruli located in the caudal end of the olfactory bulb. One of them was located in the “modified glomerular complex” reported to be involved in rat suckling behavior.The projectional patterns of the necklace olfactory system, albeit diffuse, indicated some degree of spatial correspondence between zones of olfactory epithelium and specific glomeruli. Axons emanating from neighboring cells can project to several glomerular loci. From the necklace olfactory system, an average of 150‐200 receptor cells were estimated to converge onto a single necklace glomerulus.
Neuronal and glial changes in the rat phrenic nucleus occurring within hours after spinal cord injury
Authors: Goshgarian Harry G. , Yu Xiao‐Jun , Rafols Joséa A. 
Published: January 2005

AbstractThe present study describes specific morphological changes in the normal ultrastructure of the rat phrenic nucleus which occur within 4 hours after an ipsilateral spinal cord hemisection rostral to the nucleus. Phrenic neurons were identified at EM levels by retrograde HRP labeling. Ultrastructural features of the phrenic nucleus in uninjured animals and at 4 hours and 1, 2, and 4 days after injury were qualitatively analyzed and then quantitated with a computerized morphometric system. Our results indicated that by 4 hours posthemisection, there was a significant increase in the number of double synapses. Furthermore, the number of double synapses remained significantly higher than normal at all the other posthemisection periods. A significant increase in the length of dendrodendritic membrane appositions was also noted as early as 4 hours posthemisection. The mean normal appositional length of 1.42 ± 0.09 μm increased to 1.89 ± 0.12 μm at 4 hours and further increased to 2.20 ± 0.20 μm by 1 day posthemisection. The increase in the length of membrane appositions was most likely due to an active retraction of astroglial processes from their normal position in between the dendrites. Although there was an increase in the mean length of the dendrodendritic appositions, the mean percentage of the appositions (expressed as the total number of appositions divided by the total number of dendrites in each sample) was not increased significantly over normal values during the early posthemisection periods. By 2 and 4 days posthemisection, however, the percentage of dendrodendritic appositions increased to significantly higher values than normal. Normally, 4.68 ± 0.69% of the dendrites in the phrenic nucleus were found to be in apposition, and this number increased significantly to 7.27 ± 1.06% by 2 days and 7.46 ± 0.79% by 4 days posthemisection. At these later posthemisection periods, the mean length of the appositions decreased to levels which were no longer significantly higher than normal. A distribution analysis of the length of each dendrodendritic apposition in both the normal and spinal hemisected rats showed that there were more dendrodendritic appositions in the phrenic nucleus at the later posthemisection periods. It also showed that their mean length was decreased because many of the new appositions were relatively short. The above neuronal and glial alterations of the phrenic nucleus have never before been described as a response to injury of the mammalian spinal cord. Furthermore, the possibility that the above changes could represent the morphological substrate for the unmasking of functionally ineffective synapses in our spinal cord injury model is discussed.
Terminal field of cholecystokinin‐8‐like immunoreactive projection neurons of the rat main olfactory bulb
Authors: Matsutani Shinji , Senba Emiko , Tohyama Masaya 
Published: January 2005

AbstractThe terminal field of cholecystokinin‐8 (CCK)‐like immunoreactive (CCK‐IR) tufted cells in the rat main olfactory bulb was examined by means of immunohistochemistry combined with either an anterograde tracer or a degeneration method. CCK immunostaining was carried out in animals in which Phaseolus vulgaris agglutinin (PHA) had been injected into the main olfactory bulb. Pairs of adjacent sections were processed for CCK and PHA immunostaining, respectively. Dense CCK‐IR terminallike staining was noted in layer Ia of the anterior olfactory nucleus and lateral part of the olfactory tubercle; weaker staining was also observed in the transitional area between the anterior olfactory nucleus and the piriform cortex, in the medial part of the olfactory tubercle, and in the cortical amygdaloid nucleus. The CCK‐IR staining was limited to the area containing PHA‐labeled terminals and was diminished in these sites after unilateral olfactory bulbectomy. Immuno‐electron microscopic analysis showed that CCK‐IR profiles in such regions made asymmetric synaptic contacts, mainly with dendritic spines. These results suggest that CCK‐IR tufted cells project mainly to the anterior olfactory nucleus and lateral part of the olfactory tubercle, and act mainly via axospinous synapses.
Glucocorticoid receptor‐immunoreactivity in C1, C2, and C3 adrenergic neurons that project to the hypothalamus or to the spinal cord in the rat
Authors: Sawchenko P. E. , Bohn M. C. 
Published: January 2005

AbstractA combined retrograde transport‐double immunohistochemical staining method was used to determine the extent to which rat liver glucocorticoid receptor‐immunoreactivity (GR‐ir) is contained within phenylethanolamine‐N‐methyltransferase (PNMT)‐ir neurons that project to the paraventricular nucleus of the hypothalamus (PVH) or the spinal cord. The results confirmed that cells in the C1, C2, and C3 adrenergic cell groups each contribute to the adrenergic innervation of the PVH, and indicated that the great majority of retrogradely labeled neurons in each group (80% overall) also express GR‐ir. Following injections in the upper thoracic segments of the spinal cord, the bulk of adrenergic neurons that were retrogradely labeled were found in the C1 cell group, though 31% of the total number PNMT‐ir cells that could be retrogradely labeled following spinal injections were localized in the C2 and C3 regions. Of these spinally projecting PNMT‐ir neurons, 62% displayed GR‐ir. The results suggest all three medullary adrenergic cell groups contribute projections to the spinal cord and/or the PVH, and that the capacity to express the GR phenotype is a common, though perhaps not universal, attribute of PNMT‐ir neurons. No pronounced differences in the expression GR‐ir were observed in adrenergic neurons as a function of their location or efferent projections. Brainstem adrenergic neurons may play a role in integrating neuronal and hormonal controls of adrenal function via ascending and descending projections.