bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytoskeletal specializations at the rod photoreceptor distal tip
Authors: Roof Dorothy , Adamian Michael , Jacobs Deborah , Hayes Annmarie 
Published: January 2005

AbstractWe have examined microtubules and microtubule‐like elements within the toad rod photoreceptor outer segment in order to define regional specializations of the photoreceptor cytoskeleton. “Ciliary” microtubules were localized within the rod outer segment (ROS) by using thin section electron microscopy, immunofluorescence, and rapid‐freeze deep‐etch microscopy. All three methods showed that ciliary microtubules stop short of the extreme ROS distal tip, although abundant microtubule‐like structures distinct from the ciliary microtubules were found within the distal 10–15 μm of the ROS tip. These heretofore undescribed “distal ROS tubules” are clustered at the clefts or incisures of the disk membrane stack and resemble microtubules in overall size and shape, although they are not closely related antigenically to tubulin. The distal ROS tubules are more abundant in green rods than red rods and vary in number during the daily light/dark cycle. Quantitation of these tubules at two time points during the light/dark cycle suggests that there are three‐ to fourfold more tubules in the ROS tip one hour after light onset than one hour before light onset. Retinas prevented from normal disk membrane shedding by separation of the retina from the adjacent pigment epithelium, failed to develop increased numbers of tubules after light onset. This suggests that the newly described distal ROS tubules may modulate or be modulated by light‐induced interactions between the photoreceptors and pigment epithelium, such as those that occur during the disk shedding phase of membrane turnover.
A note on the organization of the amphibian olfactory bulb
Authors: Scalia Frank , Gallousis Gregory , Roca Suri 
Published: January 2005

AbstractAfter horseradish peroxidase (HRP) injections were made in limited sectors of the main olfactory bulb in the adult frog Rana pipiens, the cellular morphology of mitral cells and granule cells impregnated with HRP were examined in uninjected regions of the bulb. Mitral cells were observed to possess glomerular dendrites and prominent secondary dendrites, both of which have smooth shafts. The glomerular dendrites may be multiple, are often branched, and may arise from secondary dendrites, as well as from the cell body. The axon may also arise from a secondary dendrite. Granule cells have simple or branched peripheral dendrites, and these are spiny, where they intermingle with the mitral cell secondary dendrites. The prominence of the secondary dendrites of frog mitral cells contrasts sharply with their reported insignificance in urodeles, as studied in earlier literature.The layers of the main olfactory bulb are not as fully concentric in the frog, as they are in mammals. The implantation cone and glomerular layer occupy a small part of the surface area of the olfactory bulb on its anteroventral aspect, while the perimeters of the subjacent layers extend farther posteriorly and dorsally in successive steps. The granule cell core extends well beyond the perimeter of the mitral cell layer in a posterior direction. Long secondary dendrites of mitral cells also extend posteriorly beyond the perimeter of the mitral cell‐external plexiform layer and interlace with granule cell peripheral dendrites in a plexiform layer external to the posterior region of the granule cell core. This layer, the superficial plexiform layer, forms an apron around the posterior segment of the olfactory bulb and contributes to the interbulbar adhesion. It appears likely that it is an extension to the microcircuitry typically confined within the external plexiform layer in mammalian species.
Distribution, laminar location, and morphology of tectal neurons projecting to the isthmo‐optic nucleus and the nucleus isthmi, pars parvocellularis in the pigeon (Columba livia) and chick (Gallus domesticus): A retrograde labelling study
Authors: Woodson Walter , Reiner Anton , Anderson Keith , Karten Harvey J. 
Published: January 2005

AbstractRetrograde transport of Phaseolus vulgaris leucoagglutinin (PHA‐L), fluorogold, fast blue, rhodamine labelled microspheres, and horseradish peroxidase (HRP) was employed to study the distribution, laminar location within the optic tectum, and morphology of tectal cells projecting upon the isthmo‐optic nucleus (ION) and the nucleus isthmi, pars parvocellularis (Ipc), in the pigeon and chick.Following injections into the ION, all retrograde markers labelled tecto‐ION neurons and their dendrites in the ipsilateral tectum. The cells were located within a relatively narrow band at the border between layers 9 and 10 of the stratum griseum et fibrosum superficial (SGFS). Retrogradely labelled neuronal somata were different in both dendritic branching and shape; however, tecto‐ION neurons generally possessed non‐spiny radially oriented and multi‐branched dendrites. The apical processes extended into the retino‐recipient layers (2–7) of the SGFS and basal dendrites extended into layers 12–14 of the SGFS. Positive neuronal somata were observed throughout the rostro‐caudal extent of the optic tectum. The average distance between adjacent tecto‐ION neurons varied from one region to another. Specifically, retro‐gradely labelled cells were more numerous in the caudal, lateral, and ventral tectum, and less numerous at rostro‐dorsal levels. Approximately 12,000 tecto‐ION neurons were labelled within the ipsilateral optic tectum following either PHA‐L or fluorescent dye injections.While the regional distribution of tecto‐Ipc neurons was not examined, the morphology indicated that the cells had a single radially oriented dendritic process. Therefore, the apical dendrites are more restricted than those of tecto‐ION cells. Moreover, the dendrites were spiny and arborized within layers 3, 5, and 9 of the ipsilateral optic tectum. The axon of tecto‐Ipc cells arise from the apical process as a shepherd's crook and descend into the deep layers of the optic tectum.These results indicate that (1) tecto‐ION and tecto‐Ipc neurons are possibly monosynaptically activated by retinal input, (2) tecto‐ION neurons are heterogeneous in morphology, and (3) there is a differential distribution of the tecto‐ION neurons throughout the rostro‐caudal extent of the optic tectum, suggesting a greater representation of the caudo‐ventral portion of the optic tectum within the ION.The discussion primarily concerns the organization of the retino‐tecto‐ION‐retinal circuit in light of the distribution and morphology of tecto‐ION neurons within the optic tectum.
Alz‐50 immunoreactive neuropil differentiates hippocampal complex subfields in Alzheimer's disease
Authors: Brady Daniel R. , Mufson Elliott J. 
Published: January 2005

AbstractThe topographic distribution of Alz‐50 containing profiles was determined within the hippocampal formation and anterior parahippocampal gyrus by using a monoclonal antibody directed against the A68 protein in normal and Alzheimer's diseased (AD) brains. Although there was a paucity of immunoreactive neuropil in the normal hippocampal complex, there were a few Alz‐50 positive neurons that occupied the hippocampal subfield, CA2. In most AD cases, Alz‐50 immunoreactive neuropil was prominent in the outer two‐thirds of the molecular layer of the dentate gyrus, although a few cases exhibited staining in the inner third of the molecular layer. CA2 was characterized by an increased density of neuropil staining within stratum pyramidale. The neuropil in subfield CA1 was stained densely with Alz‐50 in strata oriens, pyramidale, and at the border between strata lacunosum‐moleculare and radiatum. Alz‐50 immunostained neurites occupied primarily the lateral two‐thirds of the subiculum proper, whereas only sparse staining was seen in the adjacent presubiculum. Alz‐50 neuropil and neuronal staining displayed three distinct laminar patterns along the mediolateral extent of the entorhinal cortex, whereas the perirhinal cortex exhibited a bilaminar pattern of immunoreactivity involving heavy staining in layers 1–3 as compared to layer 5. In general, the density of Alz‐50 neurite staining in the neuropil appeared inversely proportional to the distribution of Alz‐50 immunoreactivity within dendritic and somal compartments. Interestingly, the patterns of Alz‐50 staining observed in the hippocampal complex in AD coincides with patterns of well‐characterized afferent fiber pathways to these regions, thus further supporting the suggestion that hippocampal subfield specific pathology effectively disconnects medial temporal structures from adjacent neocortex in AD.
Galanin‐like immunoreactivity in the brain of teleosts: Distribution and relation to substance P, vasotocin, and isotocin in the atlantic salmon (Salmo salar)
Authors: Holmqvist Bo I. , Ekström Peter 
Published: January 2005

AbstractThe presence of galanin‐like substances and their relation to substance P‐, vasotocin‐, and isotocin‐immunoreactive neurons and fibers in the brain of teleosts was investigated with immunohistochemical methods. Two specific antisera against synthetic porcine galanin (GAL) revealed cell bodies and fibers in the brain of four different teleost species (Salmo salar, Carassius carassius, Gasterosteus aculeatus, and Anguilla anguilla). In all four species the main location of galanin immunoreactivity was in the hypothalamo‐pituitary region. A detailed study of the distribution of galanin immunoreactivity in S. salar showed that galanin immunoreactive (GALir) perikarya were present in the nucleus preopticus periventricularis, an area that may be compared to the supraoptic nucleus in mammals, and in the nucleus lateralis tuberis, a nucleus involved in pituitary control in fishes that may be compared with the arcuate nucleus in mammals, GALir perikarya were found also in the nucleus recessus lateralis and in the nucleus recessus posterior. Numerous GALir fibers were present in the telencephalon and diencephalon, whereas only small numbers of fibers were found in the brainstem. In contrast to the situation in mammals, no GALir perikarya were observed in the brainstem areas corresponding to the noradrenergic locus coeruleus and serotonergic raphe nuclei in S. salar. We did not find any coexistence of GALir substances with arginine vasotocin or isotocin in neurosecretory neurons, as has been shown for galanin with the mammalian counterparts vasopressin and oxytocin. Also, the galanin‐like substance(s) and their structurally closest related peptide family, the tachykinins, belong to separate neuronal systems in teleosts. The presence of GALir neurons in brain areas known to be involved in pituitary control, and a massive GALir innervation of the pituitary, strongly indicate a role for galanin‐like substances in pituitary control also in teleosts. Furthermore, the presence of extrahypothalamic GALir fibers suggests involvement of galanin‐like substances in other brain functions in teleosts. In conclusion, there are general similarities between teleosts and mammals concerning the distribution of galanin‐like substances. However, there seem to be substantial differences in their distribution relative to functionally related peptides within the hypothalamo‐pituitary system. Whereas galanin appears to be colocalized and released together with vasopressin and oxytocin in mammals, in teleosts the homologous substances are contained within different sets of neurons that innervate the same target, the pituitary.
Projections from the periaqueductal gray to the rostromedial pericoerulear region and nucleus locus coeruleus: Anatomic and physiologic studies
Authors: Ennis Matthew , Behbehani Michael , Shipley Michael T. , van Bockstaele Elisabeth J. , Aston‐Jones Gary 
Published: January 2005

AbstractPrevious studies showed that the nucleus locus coeruleus (LC) receives two major afferent inputs from (1) nucleus paragigantocellularis and (2) nucleus prepositus hypoglossi, both in the rostral medulla. Recent reports suggested that the midbrain periaqueductal gray (PAG) projects to the rostromedial pericoerulear area and LC. Since the PAG is a major site for control of central antinociception, and since descending nonadrenergic fibers have been implicated in pain modulation, we have investigated in detail the functional anatomy of projections from PAG to the dorsolateral pontine tegmentum. A combined anatomical and electrophysiological approach was used to assess the organization and synaptic influence of PAG on neurons in the rostromedial pericoerulear region and in LC proper.Injections of the tracer wheatgerm agglutinin conjugated to horseradish peroxidase encompassing LC proper and the rostromedial pericoerulear area retrogradely labeled neurons in PAG located lateral and ventrolateral to the cerebral aqueduct; injections restricted to LC proper did not consistently label PAG neurons. Deposits of the anterograde axonal tracer Phaseolus vulgaris leucoagglutinin into this same region of PAG labeled axons that robustly innervated the zone rostral and medial to LC. Only sparse fibers were observed in LC proper. Consistent with these results, focal electrical stimulation of LC antidromically activated only a few PAG neurons (6 of 100); all of these driven cells were located lateral and ventrolateral to the cerebral aqueduct.The majority of neurons in the rostromedial pericoerulear area were robustly activated by single pulse stimulation of PAG. In contrast, single pulse electrical stimulation of lateral PAG produced weak to moderate synaptic activation of some LC neurons; stimulation of ventrolateral PAG produced predominant inhibition of LC discharge, perhaps through recurrent collaterals subsequent to antidromic activation of neighboring LC cells.Taken together, these results indicate that PAG strongly innervates the region rostral and medial to LC, including Barrington's nucleus, but only weakly innervates LC proper. Although recent studies indicate that the dendrites of LC neurons ramify heavily and selectively in the rostromedial pericoerulear region, the results of the present physiological studies suggest that PAG preferentially targets rostromedial pericoerulear neurons rather than LC dendrites.
Visual topography of area TEO in the macaque
Authors: Boussaoud Driss , Desimone Robert , Ungerleider Leslie G. 
Published: January 2005

AbstractPrevious studies have mapped the visuotopic organization of visual areas from V1 through V4 in the occipital cortex and of area TE in the temporal cortex, but the cortex in between, at the occipito‐temporal junction, has remained relatively unexplored. To determine the visuotopic organization of this region, receptive fields were mapped at 1,200 visually responsive sites on 370 penetrations in the ventral occipital and temporal cortex of five macaques. We identified a new visual area, roughly corresponding to cytoarchitectonic area TEO, located between the ventral portion of V4 and area TE. Receptive fields in TEO are intermediate in size between those in V4 and TE and have a coarse visuotopic organization. Collectively, receptive fields in TEO appear to cover nearly the entire contralateral visual field. The foveal and parafoveal representation of TEO is located laterally on the convexity of the inferior temporal gyrus, and the peripheral field is represented medially on the ventral surface of the hemisphere, within and medial to the occipitotemporal sulcus. Beyond the medial border of TEO, within cyteoarchitectonic area TF, is another visually responsive region, which we have termed VTF; this region may also have some crude visual topography. Bands of constant eccentricity in TEO appear to be continuous with those in V2, V3v, and V4. The upper field representation in TEO is located adjacent to that in ventral V4, with a representation of the horizontal meridian forming the boundary between the two areas. The lower field representation in TEO is located just anterior to the upper field but is smaller. In contrast to the orderly representation of eccentricity in TEO, we found little consistent representation of polar angle, other than the separation of upper and lower fields. The results of injecting anatomical tracers in two animals suggest that TEO is an important link in the pathway that relays visual information from VI to the inferior temporal cortex. TEO is thus likely to play an important role in pattern perception.
Volumetric and histological changes in the cochlear nuclei of visually deprived rats: A possible morphological basis for intermodal sensory compensation
Authors: Dyson Susan E. , Warton Svetlana S. , Cockman Brett 
Published: January 2005

AbstractThe cochlear nucleus of 90 day‐old rats was studied to determine whether bilateral visual deafferentation at birth induced compensatory structural changes in the auditory system.Computer‐assisted reconstructions of the cochlear nucleus ware used to demonstrate the three‐dimensional organization of the nucleus and for calculating volumes of the subdivisions. In enucleated rats the volume of the granular region of the nucleus (GCD) increased 22.6% relative to controls, and the volume of the anterior ventral nucleus (AVCN) also increased by 10.0%. The posterior ventral nucleus (PVCN) and dorsal nucleus (DCN) were not affected.Since the volume change in GCD was substantial, this region was subjected to further analysis, Two types of granular cells were identified in the GCD of both control and enucleated rats with Kluver‐Barrera staining. Type 1 cells contained an ovoid dark nucleus with clumpy chromatin and possessed only a very thin rim of cytoplasm. Type 2 cells were larger with pale spheroidal nuclei and with a more prominent cytoplasmic rim. There was an obvious stratification of these two cell types in the superficial layers over the lateral aspect of the AVCN in both groups. In contrast to this, the subpeduncular corner was not distinctively laminated and contained predominantly Type 2 cells. In enucleated animals the nuclear size of Type 1 cells increased by 3.8% while the size of Type 2 nuclei was not affected.Granule cell numbers increased by 28% in the visually deafferented rats. The GCD seems to be more highly developed in species which are dependent on non‐visual modalities for spatial location. The regional hypertrophy of the GCD and AVCN seen in the present study may indicate that intermodal sensory compensation is taking place in the auditory system of visually deafferented rats.
Morphological organization of rat hippocampal slice cultures
Authors: Caeser Manfred , Aertsen Ad 
Published: January 2005

AbstractUsing various histological methods, we investigated the cellular and morphological organization of rat hippocampal slice cultures. Many of the typical features of the hippocampus were retained in vitro over a long period of time. The principal cell types of the hippocampus and dentate gyrus, the pyramidal cells and granule cells, were well preserved and matured in vitro. Nonpyramidal cells and γ‐aminobutyric‐acid (GABA) cells were also present in slice cultures and exhibited a strikingly similar dendritic appearance at the light microscopic level. Moreover, GABA‐immunoreactive cell bodies and presynaptic terminals could be identified at the electron microscopic level; they expressed typical symmetric synaptic contacts with cell bodies and dendrites. The course of the intrinsic hippocampal fiber pathways—the mossy fibers, Schaffer collaterals, and alveus–was generally retained in vitro. Additional aberrant fiber projections could be identified. Finally, three types of nonneuronal cells could be distinguished on the basis of immunocytochemical methods.
An electron microscopic, immunogold analysis of glutamate and glutamine in terminals of rat spinocerebellar fibers
Authors: Ji Zhongqi , Aas Jan‐Erik , Laake Jon , Walberg Fred , Ottersen Ole Petter 
Published: January 2005

AbstractA semiquantitative, electron microscopic immunocytochemical procedure based on the use of colloidal gold particles as markers was employed to analyze the subcellular distribution of glutamate and glutamine, a major glutamate precursor, in a subpopulation of spinocerebellar mossy fiber terminals. These terminals were identified by anterograde transport of a horseradish peroxidase‐wheat germ agglutinin conjugate, injected in the thoracic spinal cord. Gold particles signalling glutamate‐like immunoreactivity were enriched over clusters of synaptic vesicles relative to organelle‐free cytoplasmic matrix, and there was a strong positive correlation between gold particle and synaptic vesicle densities (correlation coefficient 0.94). Gold particles indicating glutamine‐ike immunoreactivity showed a much weaker correlation with vesicle density (correlation coefficient 0.36) and were about equally concentrated over cytoplasmic matrix as over clusters of synaptic vesicles.Compared with the mossy fibers, the putative GABAergic Golgi cell terminals exhibited a lower level of glutamate‐like immunoreactivity, which was very weakly correlated with the vesicle density (correlation coefficient 0.27). The level of glutamine‐like immunoreactivity in the Golgi cell terminals was similar to that in mossy fibers, but much lower than that in glial cells.The anterogradely labelled mossy fiber terminals were not enriched in immunoreactivities for aspartate or GABA.These results suggest that the level and subcellular distribution of glutamate in presumed glutamatergic terminals differs from that in terminals in which glutamate only serves metabolic or precursor roles, and that these differences can be exploited in immunocytochemical studies aimed at identifying glutamate‐using neurons. In contrast, glutamine immunocytochemistry does not seem to be generally useful in this regard.
The optic tectum of the dogfish Scyliorhinus canicula L.: A Golgi study
Authors: Manso M. Jesús , Anadon Ramón 
Published: January 2005

AbstractThe optic tectum of the dogfish Scyliorhinus canicula L. was studied by using the methods of Nissl, reduced silver nitrate, Golgi‐aldehyde, and Golgi‐Cox. Six layers and eight types of neurons were recognized. These cell types are not restricted to one layer; in fact some are found in all six tectal layers. The types of cells found are A) monopolar, B) triangular, C) radial bipolar, D) horizontal fusiform, E) large tectal, F) small tectal, G) pyriform, and H) stellate cells. In at least six of the cell types a series of dendritic specializations can be observed, such as spines in the form of “drumsticks” and thin varicose appendages, similar to those reported previously in the optic tecta of amphibians and teleosts. The optic tectum of the dogfish shows a degree of complexity comparable to that of amphibians and teleosts.