bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ontogeny of the peptidergic system in the rat spinal cord: Immunohistochemical analysis
Authors: Senba Emiko , Shiosaka Sadao , Hara Yoshinobu , Inagaki Shinobu , Sakanka Masahiro , Takatsuki Kenichi , Kawai Yuriko , Tohyama Masaya 
Published: January 2005

AbstractThe ontogeny of neuropeptides, such as somatostatin (SRIF), substance P (SP), leucine‐enkephalin (LE), and neurotensin (NT) in the spinal cord (including the spinal ganglion) of the rat, was examined by means of the indirect immunofluorescence method. SRIF and SP appear in the early fetal period before the establishment of the spinal synaptic transmission system, and their appearance precedes that of LE and NT, thus suggesting that SRIF and SP might have some important role in the development of the spinal cord. Furthermore, a number of SRIF‐positive structures are found during the fetal period in the spinal cord; however, SRIF‐positive fibers in the ventral horn, lamina V, VI, and X tend to decrease remarkably in number after birth, while those found in the dorsal horn maintain their immunoreactivity even in the adult rats. These facts suggest that SRIF in the latter area might function as a neurotransmitter, whereas in the former areas, SRIF might have another role in the development of the spinal cord. SP‐positive structures also made their appearance during the fetal period. SP‐positive fibers continue to increase in number after birth, and they can be seen throughout the entire spinal cord even in the adult rats. It becomes difficult to identify SP‐positive neurons as the rats grow. Numerous SP‐positive cells are demonstrated, however, by colchicine pretreatment, thus suggesting that this system is functioning actively in the adult rats. LE‐and NT‐positive structures appear at perinatal stages and they continue to increase in number after birth. These facts suggest that these peptides (SP, LE and NT) might act as neurotransmitters.
The organization of the thoracic spinal nerve projection in the rat dorsal horn demonstrated with transganglionic transport of horseradish peroxidase
Authors: Ygge J. , Grant G. 
Published: January 2005

AbstractTransganglionic transport of horseradish peroxidase (HRP) was used to study the organization of the thoracic spinal nerve projection to the dorsal horn in rats. Labeling was found in the superficial dorsal horn 16–20 hours after application of HRP to the cut ends of various spinal nerve rami. Labeling was restricted to the outer part of the substantia gelatinosa at these stages. Longer survivals (25–48 hours) gave rise to labeling of the deep part of substantia gelatinosa and deeper parts of the dorsal horn as well. The dorsal ramus projected to the lateral third of the horn from half a segment rostral to half a segment caudal to the entry segment. The ventral ramus projected to the medial two‐thirds of the horn from 1 1/2 segments rostral to half a segment caudal to the entry segment. The two branches of the ventral ramus that were examined projected to separate medial and lateral compartments for the entire ventral ramus. There was a distinct laterp‐medial shift of the projection found from rostral through caudal levels within the projection compartment for each nerve.The results indicate that the dorsal horn projection of thoracic spinal nerve branches is organized in longitudinal compartments which are arranged in a strictly somatotopic fashion.
The evolution of an area and visual streak in the marsupial Setonix brachyurus
Authors: Beazley L. D. , Dunlop S. A. 
Published: January 2005

AbstractThe distribution, morphology, size, and number of cells in the retinal ganglion layer of the marsupial Setonix brachyurus, “quokka,” was studied from 25 days postnatal to adulthood using Nissl‐stained wholemountsThe total cell population was evenly distributed up to 50 days, but by 75 days highest densities were generally observed in a broad band extending across the nasotemporal axis. At 87 days, a temporally situated area centralis was seen for the first time. This was embedded in a horizontally aligned visual streak, the nasal arm of which contained areas of high density. By 106 days, densities in the area centralis had stabilized while peripheral values were higher than adult levels even at 180 days. In the adult, the area centralis was surrounded by a weak visual streak Retinal area increased steadily during development to reach 168 mm2 180 days, the adult range being 225–250 mm2All cells in the ganglion layer appeared undifferentiated and rounded at 33 days with soma diameters of 3‐6 μm; by 70 days diameters had increased to 4‐12 μm and some cells had axon hillocks containing Nissl substance. From 87 days we distinguished ganglion cells, which constituted 54‐63% of the total. These were identified by deeply stained Nissl substance and had diameters of 7‐18 μm, compared to 7–23 μm at 143 days and 7‐24 μm in the adult; the remaining cells, termed glia/interneurons, were 5–8 μm throughout. Only ganglion cells were organized into an area centralis and visual streak. Glia/interneurons were evenly distributed except at the extreme periphery, where their density increased. In sectioned material, the ganglion layer was distinct from 25 days while the neuroblastic layer separated only between 48 and 85 daysFrom 25 to 250 days the total number of cells in the ganglion layer remained similar to the adult range of 336, 000‐393, 000. At both 87 days and in adults optic axon counts fell between 180, 000 and 224, 000, close to ganglion cell estimates. At 25 and 34 days, respectively, optic axon numbers were 75, 000 and 172, 000. Myelination was absent at 25 and 34 days, 3% at 87 days, and almost 100% in adultsMechanisms are discussed whereby the area centralis and visual streak may evolve from an even distribution of cells while their number remains constant; migration is considered likely to be important.
The ultrastructure of rat rod synaptic terminals: Effects of dark‐adaptation
Authors: Brandon Christopher , Lam Dominic M.‐K. 
Published: January 2005

AbstractThe ultrastructure of synaptic terminals of rat rod photoreceptors was studied in light‐adapted and dark‐adapted states. In the light‐adapted state, horizontal cell processes embedded in the photoreceptor terminal show smooth surface contours and are ovoid in cross section. In the dark‐adapted state, fingerlike protrusions of photoreceptor cytoplasm extend into the horizontal cell processes on either side of the synaptic ribbon. An electron‐dense structure lies under the horizontal cell membrane that surrounds these fingerlike protrusions. This submembrane specialization is generally associated with areas of concavity of the horizontal cell membrane; it occurs in goldfish rods as well as rat rods. The protrusions and the horizontal cell specialization may be involved in membrane dynamics during synaptic activity.
The number of neurons in the different laminae of the binocular and monocular regions of area 17 in the cat
Authors: Beaulieu Clermont , Colonnier Marc 
Published: January 2005

AbstractThe number of neurons in individual laminae of area 17 was determined separately for both the binocular and the monocular, regions in the left hemi‐sphere of six cats. The number of neurons/mm3 of tissue was obtained for each lamina by using the method of size‐frequency distribution applied to neuronal nuclei. The number of neurons per unit of cortical surface could then be calculated from measurements of layer, thickness. The number of neurons/mm3 of tissue for trie total cortical thickness is on the order of 48,000 to 50,000 neurons, with no statistically significant differences be‐tween binocular and monocular regions. There are no significant differences for any of the layers except layer IV, in which the numerical density is 20% higher in the monocular region. The thickness of the cortex and of many of its layers, however, do vary between the two regions. Consequently there are significant differences in the number of neurons under 1 mm2 the total cortical thickness there are significantly more (27%) neurons in the binocular (78,440) than in the monocular region (61,900). This overall difference is due to significant changes in layers II, IIIA, IVA, and especially in layers V and VIA where neurons are 40% more numerous in the binocular region. These findings could signify either that the binocular region contains additional interneurons specifically related to binocular interactions or that it has a greater number of neurons projecting to other cortical and subcortical areas, or both.
Development of fetal retina, tectum, and cortex transplanted to the superior colliculus of adult rats
Authors: McLoon Steven C. , Lund Raymond D. 
Published: January 2005

AbstractEarlier studies showed that embryonic retina, cortex, or tectum transplanted adjacent to the superior colliculus of newborn host rats differentiated many of the histological features appropriate for the donor region and developed interconnections with the host nervous system. In the study presented here, the same regions were transplanted to the brain of adult host rats and the development of these transplants was compared to those into newborn hosts. Retina, rostral tectum, or occipital cortex was dissected from donor rat embryos on gestational day 14 or 15. A portion of cortex was aspirated in 2‐;menth‐old host rats to expose the right superior colliculus, and one of the donor tissues was placed adjacent to the colliculus in each host. Two to 4 months after transplantation, transplant histology and neuronal interconnections between the transplant and host nervous system were studied by using Nissl and neurofibrillar stains and 3H‐proline and HRP tract tracing techniques.Four main points can be drawn from these results. First, 80% of the transplants survived in adult hosts –a percentage comparable to that found in newborn hosts. Second, each of the types of tissues transplanted differentiated histological characteristics appropriate for its site of origin, although the degree of differentiation was always much less than in transplants to newborns. Third, the transplants developed only relatively local projections into the host cortex and superior colliculus. This contrasts with the extensive projections found from the transplants into the brain of newborn hosts. Fourth, no definitive projections from the host retina or brain were identified to any of the transplants into adults, whereas both cortical and tectal transplants into newborns received projections from the host.
Ontogeny of cholecystokinin‐8‐containing neuron system of the rat: An immunohistochemical analysis. I. Forebrain and upper brainstem
Authors: Cho Hee Jung , Shiotani Yahe , Shiosaka Sadao , Inagaki Shinobu , Kubota Yoshiyuki , Kiyama Hiroshi , Umegaki Kanji , Tateishi Kayoko , Hashimura Etsuo , Hamaoka Toshiyuki , Tohyama Masaya 
Published: January 2005

AbstractOntogeny of the cholecystokinin‐8 (CCK) neuron system in the fore‐brain and upper brainstem of the rat was investigated by means of indirect immunofluorescence. CCK ceils and fibers first appeared in the developing ventral tegmental area and in the primordium of the medial forebrain bundle, respectively, at gestational day 15 (12–14‐mm embryos). From that time, CCK cells appeared in various areas of the forebrain and upper brain‐stem until birth and reached the maximum content at postnatal day 10. After postnatal day 10, although CCK cells tended to decrease slightly in number, colchicine treatment in the adult rats brought out numerous CCK cells in the same areas. In contrast, although CCK fibers developed only slightly during the fetal period, marked development was seen after birth, particularly between postnatal days 5 and 10. After that time, as the rats grew, CCK fibers continued to increase in number and formed a meshwork of varying density in various areas of the forebrain and upper brainstem.
The specificity of central nervous projections of locust mechanoreceptors
Authors: Bräunig P. , Pflüger H.‐J. , Hustert R. 
Published: January 2005

AbstractThe central projections of hairplates and groups of campaniform sensilla of various parts of the locust head, neck, and thorax are compared. Receptors with approximately the same peripheral location (e.g., dorsal head, wing, or proximal leg) tend to exhibit similar central projection patterns. Specificity of the projections due to different morphological types of sensory neurones may influence shape and extent of segmental ramifications; this is observed with receptors of the proximal leg joints in particular.
The relationship between retinal axon ingrowth, terminal morphology, and terminal patterning in the optic tectum of the frog
Authors: Constantine‐Paton Martha , Pitts Eleanor C. , Reh Thomas A. 
Published: January 2005

AbstractThe mode of entry of retinal ganglion cell (RGC) axons and the detailed morphology of their arbors has been studied in the tectal lobes of the frog Ranapipiens. These tecta were subjected intact to HRP histochemistry and subsequently flal‐mounted for examination under a compound microscope. Subsets of RGC axons were labelled by inserting small pellets of solidified HRP into the optic chiasm region or into the tectal neuropil itself. Annular or semiannular patterns of retinal ganglion cell arbors were always observed after placement of HRP in the chiasm region. HRP pellets in the tectal neuropil labelled segments of annuli in caudal tectal regions. These tectal patterns corresponded to a similar annular distribution of HRP‐filled RGC bodies in the topographically appropriate regions of the contralateral retina.The morphologies and trajectories of RGC axons were found to vary systematically depending on the age of the animal and the region of the tectal lobe examined. In rostral tectum the tangential spread of large‐caliber RGC axon arbors appears to decrease with increasing animal age and in large adult frogs there is a general tendency for arbors in caudal tectum to be larger than arbors in rostral tectum. In addition, axons contributing to terminal annuli in the central region of young and old frog tecta travel in a strict rostrocaudal direction over the anterior regions of the lobe. A predominantly rostrocaudal trajectory is also established by axons terminating in lateral and medial regions of the tecta of young postmetamorphic frogs. In the lateral and medial regions of mature optic tecta, however, axons arborizing in peripheral terminal annuli turn rather abruptly off the medial and lateral optic tracts and establish radially oriented trajectories. The annular patterning of terminal arbors and the age‐ and position‐dependent differences in arbor morphology are discussed in the context of a developmental sequence where arbors from newly arrived RGC axons distribute themselves along the tectal borders.The question of whether such a high degree of fiber and terminal ordering actually dictates synaptic patterning in the tectal lobe has also been addressed in this study by using the stereotyped striped pattern found in the dually innervated tectal lobes of three‐eyed frogs (Constantine‐Paton and Law, 78;Law and Constantine‐Paton, '81). The presentresults indicate that eye‐specific segregation in the terminal zone is independent of bundling of axons in the optic tract. Stripes are also shown to be independent of the path taken by axons en route to the tectum and of the way in which axons enter the tectal plate. These observations and our earlier conclusions (Reh et al., '83) concerning order in the Rana optic nerve are discussed in terms of recent models of retino tectal development which postulate a role for passive “extra‐tectal” factors in the formation of this visual map.
The inferior colliculopontine neurons of the cat in relation to other collicular descending neurons
Authors: Hashikawa Tsutomu 
Published: January 2005

AbstractCells of origin of the pontine afferents from the inferior colliculus (IC) of cats have been identified by means of retrograde axonal transport of horseradish peroxidase (HRP). Following injections of HRP in the pontine nuclei, many labeled neurons were found ipsilaterally in the caudal parts of the external and pericentral nuclei, while a few cells were found in the central nucleus. Additional neurons occurred in the nuclei of the middle and rostral parts. This organization contrasts with that of other collicular descending systems. Thus, neurons projecting to the superior olivary complex and cochlear nuclei were found predominantly in the central nucleus bilaterally. In the external nucleus labeled cells tended to be distributed in the middle to rostral regions, but they were few in number in the caudal part.Since the locations of IC‐pontine neurons are found to be different from those of other IC descending neurons, it may be assumed that the IC‐pon‐ tine system does not share common functional properties with the other collicular descending neurons. Functional aspects of the IC‐pontine neurons are discussed, with a comment on a pathway for the transmission of auditory impulses to the midvermal area of the cerebellum.
Central distribution of afferent and efferent components of the pudendal nerve in cat
Authors: Ueyama Teizo , Mizuno Noboru , Nomura Sakashi , Konishi Akira , Itoh Kazuo , Arakawa Hisao 
Published: January 2005

AbstractCentral distribution of afferent and efferent components of the pudendal nerve was examined in the cat by the HRP method after applying HRP to the central cut end of the pudendal nerve.Retrogradely labeled neuronal cell bodies were located primarily in the feline homologue of the Onuf's X nucleus, constituting a slender longitudinal cell column in the ventral horn of the S1 and S2 cord segments. The Onuf's nucleus was present constantly from middle S1 to high S2 cord segments, and occasionally extended rostrally to high S1 or low L7, and caudally to middle S2, low S2, or high S3 cord segments. No sex differences were observed in the distribution pattern, number, and soma size of labeled neurons in the Onuf's nucleus.Transganglionically labeled dorsal root fibers were found to terminate ipsilaterally in the lamina I of the dorsal horn at levels of lower lumbar, sacral, and higher coccygeal cord segments and the gracile nucleus, and bilaterally with an ipsilateral predominance in the dorsal commissural gray and laminae III, IV, V, and VI of the dorsal horn at levels of lower lumbar, sacral, and higher coccygeal cord segments. Some labeled dorsal root fibers appeared to end ipsilaterally in the regions where the sacral parasympathetic preganglionic neurons have been shown to be located.
Electrical and morphological properties of off‐center bipolar cells in the carp retina
Authors: Saito Takehiko , Kujiraoka Toru , Toyoda Jun‐Ichi 
Published: January 2005

AbstractElectrical membrane properties of carp off‐center bipolar cells were studied by injecting a ramp of current (changing at a rate of about 0.3 nA/s) through one barrel of a double‐barreled electrode and recording the voltage drop through the other barrel. The light‐elicited response reversed the polarity at a positive membrane potential. The current‐voltage curve showed inward and outward rectifications which modified the amplitude of the light‐elicited response. The degree of membrane rectifications varied considerably among the cells sampled.Off‐center bipolar cells were stained by iontophoretic injections of Lucifer‐yellow dye after studying their electrical properties. There was a significant correlation between the difference in cell morphology and the degree of membrane rectification. The cells, which were characterized by small cell bodies lying close to the proximal part of the inner nuclear layer and by thin primary dendrites, tended to show rectifying membrane properties, compared to those characterized by large cell bodies lying close to the distal part of the inner nuclear layer and by thick primary dendrites. A site showing rectifying membrane properties and the origins of a large variability in membrane rectifications are discussed in detail.
The neuronal architecture of the inferior colliculus in the cat: Defining the functional anatomy of the auditory midbrain
Authors: Morest D. Kent , Oliver Douglas L. 
Published: January 2005

AbstractThis study defines anatomical subdivisions in Golgi‐impregnated material from the inferior colliculus of the cat. The findings demonstrate that the inferior colliculus consists of a mosaic of morphologically distinct parts of neuropil. Each part is also characterized by a unique set of neuronal types.Each part of the inferior colliculus can be defined as tectal or tegmental on the basis of the fundamental pattern of dendritic branching. The main subdivisions of the auditory tectum are the central nucleus, the cortex, and the paracentral nuclei. The central nucleus is distinguished by its laminated neuropil composed of neurons with disc‐shaped dendritic fields oriented in parallel arrays with the lemniscal axons. In contrast, the cortex is identified by its broad layers of loosely woven neuropil, which are orthogonal to those in the central nucleus and lack neurons with disc‐shaped dendritic fields. The paracentral nuclei, so called because of their scattered arrangement around the central nucleus, are the commissural, dorsomedial, rostral pole, lateral, and ventrolateral nuclei. The main subdivisions of the auditory tegmentum are the pericollicular areas, the nucleus of the brachium of the inferior colliculus, and the sagulum. The pericollicular areas are intercollicular or subcollicular and separate the tectal division from the superior colliculus, central gray, and remaining portions of the tegmentum. The afferent projections to each tectal and tegmental subdivision, as observed in silver‐degeneration experiments, distinguish the parcellations based on the Golgi findings. Subdivisions containing tectal cell types receive afferents predominantly from the auditory pathways, in contrast to subdivisions with tegmental cell types, which receive inputs from a wide variety of sources. This suggests a correlation between neuronal types and the nature of their inputs.This analysis of the subdivisions of the inferior colliculus differs from previous studies, especially those relying on Nissl stains. It is likely that subdivisions distinguished by the pattern of the neuropil differ functionally, since the structural components identified in the Golgi‐impregnated material are essential parts of the synaptic organization of the auditory midbrain. Future physiological studies should benefit from approaches in which the cell types serve as the focus for the analysis.