bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of visual deprivation on the optic centers of growing and adult mice
Authors: Gyllensten Lars , Malmfors Torbjörn , Norrlin Marie‐Louise 
Published: January 2005

AbstractThe thickness of the visual cortex, the diameter of cell nuclei and the mean volume of internuclear material per nucleus in the visual cortex, geniculate bodies and superior colliculi were determined in growing and adult mice. The influence of prolonged stay in complete darkness was investigated.In the visual cortex of normal mice, a peak in nuclear size occurred 20–30 days after birth, followed by a peak in relative volume of internuclear material.In growing mice, reared in darkness from birth, a highly significant decrease in relative volume of internuclear material occurred in all visual centers. The decrease was greatest in the geniculate bodies and greater in the granular and supragranular layers of the cortex than in the infragranular. In the cortex, the decrease was most pronounced after two months and became less pronounced during prolonged stay in darkness. No similar normalization was observed in subcortical visual centers. In the same mice, visual deprivation caused a highly significant decrease in the thickness of the visual cortex and in the diameter of its cell nuclei. The decrease in nuclear diameter was greater in the granular and supragranular than in the infragranular layers of the cortex and exhibited a similar normalization during prolonged stay in darkness as the decrease in relative volume of internuclear material.In adult mice, visual deprivation caused decrease in internuclear material.
An experimental study of the accessory optic system and of other optic fibers in the opossum, Didelphis Virginiana
Authors: Giolli Roland A. 
Published: January 2005

AbstractA study of experimental degeneration of the accessory optic system in a primitive mammal, the opossum, was undertaken in order the clarify several points regarding fiber organization and to allow comparisons to be made with this system in more advanced mammals and non‐mammalian vertebrates. The other portions of the optic system were also studied but not in great detail, since the findings were in basic agreement with those of Bodian ('37) in opossum. An eye was enucleated in each of five opossums which was sacrificed 7–12 days later. The Nauta‐Gygax technique was used to show that in opossum the accessory optic system consists essentially of one pair of tracts and terminal nuclei. Fibers of this system cross in the optic chiasma and leave the optic tract midway between the chiasma and the lateral geniculate nucleus to course caudally on the surface of the medial third of the cerebral peduncle. They intermingle with the fibers of the superficial division of the tractus geniculatus descendens and then enter the nucleus of the transpeduncular tract to terminate.The findings on the structure of the accessory optic system in opossum are in basic agreement with those in reptiles and birds. Comparison with studies in more advanced mammals indicates that this system has undergone striking changes in the topographical organization of its fibers.
Autoradiographic and histological evidence of postnatal hippocampal neurogenesis in rats
Authors: Altman Joseph , Das Gopal D. 
Published: January 2005

AbstractIn the autoradiograms of young rats injected with thymidine‐H3 many of the granule cells of the dentate gyrus were found labeled. The number of labeled cells declined rapidly with increased age at the time of injection. Histological studies showed the presence in young rats of a large germinal matrix of mitotic cells in the ependymal and subependymal layers of the third and lateral ventricles. The areal extent and cell population of this germinal pool declined rapidly from birth on, with a transient rise with a peak at about 15 days. During this latter period the number of “undifferentiated” cells near the granular layer of the dentate gyrus showed a rapid rise with a subsequent decline. The decline in the number of “undifferentiated” cells was accompanied by a rise in the number of differentiated granule cells. Cell counts in homologous parts of the dentate gyrus indicated a six‐fold increase in the number of differentiated granule cells from birth to three months. We postulated that undifferentiated cells migrate postnatally from the forebrain ventricles to the hippocampus where they become differentiated. The possible functional significance of delayed hippocampal neurogenesis is discussed with reference to our finding of incorporation of testosterone‐H3 by cells of the hippocampus, implicating that they may function as receptors of gonadal hormones.
Distribution of corpus callosum and anterior commissure in cat and raccoon
Authors: Ebner Ford F. , Myers Ronald E. 
Published: January 2005

AbstractThe distribution of the forebrain commissures was studied using the Nauta‐Gygax silver technique. Following total forebrain commissure transection in the cat the striate cortex or visual area I was remarkably free of degenerating fibers, while peristriate or visual area II showed dense degeneration. Somatic sensory arm and distal hindlimb areas appeared degeneration free while proximal leg and face areas revealed heavy degeneration. The somatic motor area of the anterior sigmoid gyrus contained dense numbers of degenerating fibers. The auditory areas of ectosylvian gyrus showed moderate degeneration over their entire surface except the most ventrally situated cortical areas which were degenerated free. Fibers from the corpus callosum also terminated in the dorsolatearal portions of the head of the caudate nucleus. The anterior limb of anterior commissure distributed mainly to the inner granular layer of the olfactory bulb. In addition, it disseminated considerable numbers of fibers in the anterior olfactory nucleus. The accessory olfactory bulb was degeneration free. The distribution of the forebrain commissures in the raccoon was very similar to the cat. The outstanding feature of the commissural pattern in the raccoon was the total absence of degenerating fibers in the lobular complex relating to the digits of the forepaw.
Distribution of optic fibers in the cat
Authors: Singleton Mary C. , Peele Talmage L. 
Published: January 2005

AbstractThis study undertook to investigate pathways and connections of optic tract fibers in the pulvinar, hypothalamus, ventral lateral geniculate, pretectal region and superior colliculus.Thirty‐five adult cats were utilized — 28 experimental subjects and seven controls. The right eye was removed and the cats allowed to survive for periods from three to 61 days. The chief method of investigation was the silver impregnation technique of Nauta‐Gygax ('54), supplemented by Marchi and luxol‐blue cresyl‐fast‐violet methods.Study of fiber patterns of degeneration in serial sections of the Nauta‐Gygax preparations revealed no preterminal axonal degeneration in the hypothalamus or pulvinar. Portions of a completely crossed accessory optic tract as described by Hayhow ('59) were identified. Preterminal degeneration of fine collaterals of the larger optic fibers was found in the dorsal one‐third of the lateral portion of the ventral lateral geniculate. Large areas of preterminal degeneration and many fibers of passage were observed in the pretectal region. Localized areas of pretermimal degeneration in this region were interpreted as belonging to the pretectal nucleus and to the nucleus of the optic tract. A large number of fine optic fibers was found terminating in the superficial stratum opticum of the superior colliculus. Two areas of preterminal degeneration lateral to the colliculus were interpreted as extension of the pretectal nucleus and as the nucleus olivaris colliculi.
Cellular localization of monoamines in the area postrema of certain mammals
Authors: Fuxe Kjell , Owman Christer 
Published: January 2005

AbstractThe area postrema was studied using a highly sensitive and specific fluorescence microscopical method for the demonstration of certain biogenic monoamines. In all the species studied (rat, guinea‐pig, rabbit, cat, dog, monkey) there occur small nerve cells containing a primary catecholamine. A varying number of catecholamine‐storing nerve terminals can be demonstrated in all species. Many — if not all — of these seem to derive from catecholamine axons running in abundance just outside the area postrema.Against the background of earlier findings (Vogt, '54; Amin, Crawford and Gaddum, '54) of high levels of noradrenaline and 5‐hydroxytryptamine thought to be present in glial cells in this organ it is concluded that these levels are not in accordance with the relatively small number of monoamine‐containing structures demonstrated in area postrema. The explanation for this is in all probability that the area postrema tissue taken for biochemical determinations have been contaminated with surrounding brain tissue, very rich in catecholamine and 5‐HT containing terminals.There is discussed in conclusion the possibility of adrenergic mechanisms being involved in the reflex path of central emesis.
Hematic and fluid barriers in the optic nerve
Authors: Rodriguez‐Peralta Lorenzo A. 
Published: January 2005

AbstractHematic and fluid barriers in the optic nerve have been studied by tracing the in vivo penetration of diaminoacridines in tissue nuclei and tissue fluids. Diaminoacridines were administered at non‐toxic doses and were detected by the fluorescence they produced when properly excited.Diaminoacridine concentrations of 10−6M or higher in circulating blood failed to penetrate into tissues and fluids protected by hemato‐encephalic or hemato‐ocular barriers. However, fluoresence was found in: (a) optic nerve dura mater including the mesothelium lining its inner surface, but not in the subjacent arachnoid, pia, or cerebrospinal fluid; (b) all orbital and dural vessel walls, including their endothelium, but not in the pial nor optic nerve vessel walls; (c) choroid, sclera, and Kuhnt's tissue, but not in the optic nerve.Diaminoacridine concentrations of 10−6M in cerebrospinal fluid produced fluorescence in optic nerve tissues and vessels, including their endothelium, and meninges, including dural mesothelium, but not in retina or vitreous. Similar concentrations in the vitreous showed fluorescence in the retina and optic nerve head tissues, but not farther in the optic nerve.Thus: (a) there is a blood‐optic nerve barrier; (b) this barrier is located in the mesothelium lining the inner dural surface, in pial and optic nerve vessels endothelium, and Kuhnt's tissue; (c) endothelium and mesothelium showed one‐way permeability; (d) there is a vitreous optic‐nerve barrier preventing passage of fluids from optic nerve to vitreous or vice versa.
Histogenesis of the nuclei griseum pontis, corporis pontobulbaris and reticularis tegmenti pontis (Bechterew) in the mouse an autoradiographic study
Authors: Pierce Elizabeth Taber 
Published: January 2005

AbstractBy means of autoradiography the time, site of origin and migration pathways of neuroblasts destined for three nuclei in the hindbrain of the mouse have been determined. The cells of the nuclei griseum pontis and corporis pontobulbaris arise on gestation days 12 through 16 in the rhombic lip from the obex to the lateral recess. Most cells migrate within 48 hours via the pontobulbar body to the base of the pons to form the nucleus griseum pontis; some migrate only a short distance along the pathway and collectively form the nucleus corporis pontobulbaris. Most cells of the nucleus reticularis tegmenti pontis (Bechterew) arise in the primitive basal ependymal plate of the pons on gestation days 12 and 13 and migrate ventrally into the tegmentum. Some probably arise at the rhombic lip and migrate via the pontobulbar body to the base of the pontine flexure where they turn dorsally into the tegmentum.
Some olfactory pathways in the rabbit brain
Authors: Scalia Frank 
Published: January 2005

AbstractThe degeneration pattern in the rabbit following transection of the olfactory bulb or peduncle at various levels was studied by the Laidlaw method of Nauta. Degenerating axons were observed in the crossing of the anterior limb of the anterior commissure and in the lateral olfactory tract following olfactory bulb lesions which did not damage the anterior olfactory nucleus. Evidence was found for termination of the olfactory tract fibers over all parts of the anterior olfactory nucleus, the rostral and lateral parts of the olfactory tubercle, the anterior continuation of the hippocampus, the nucleus of the lateral olfactory tract, and the prepyriform areas 1, 2, and 3, the periamygdaloid areas 1, 2, part of 3, and 5, and the entorhinal axeas 1, 2, and 4 of Maximillian Rose. When the anterior olfactory nucleus was damaged degeneration was found in the contralateral olfactory bulb and anterior olfactory nucleus and parts of the ipsilateral neocortex adjacent to the rhinal fissure, limbic system (medial septal nucleus and anterior continuation of the hippocampus), pyriform lobe cortex, and lateral preoptic area. The results differ in particulars from those of previous investigators.
The ultrastructure and innervation of rat vibrissae
Authors: Patrizi G. , Munger B. L. 
Published: January 2005

AbstractThe innervation of rat vibrissae has been studied by light and electron microscopy. Nerve fibers enter the external root sheath and become associated with Merkel cells. Merkel cells are specialized sheath cells containing many secretory granules apposed to the neurite. These secretory granules are PAS‐positive and diastase‐resistant in light microscopic preparations. The neurite at the level of the Merkel cell is expanded and contains masses of mitochondria. As contrasted to nerve fibers in glabrous skin, the neurite does not penetrate deeply into the external root sheath but appears to terminate at the level of the Merkel cells. The neurite‐Merkel cell complex is interpreted as representing a mechanoreceptor.
Electron microscopy of the effect of gram‐negative endotoxin on the blood‐brain barrier
Authors: Carlyle Clawson C. , Francis Hartmann J. , Vernier Robert L. 
Published: January 2005

AbstractStudies with the light microscope (Am. J. Path., 34: 631, '58) indicated that an injection of endotoxin into the carotid artery of a rabbit alters the blood‐brain barrier allowing the distribution of subsequently injected colloidal iron throughout the cerebral cortex. The present investigation by electron microscopy determined the distribution of the colloidal iron oxide in the normal and endotoxin altered cerebral capillaries of rabbits. Four hours prior to the intracarotid injection of saccharated iron oxide the animal received an injection via the same artery of either 50 μg gram‐negative endotoxin or a control dose of normal saline. The animals were sacrificed at times from 15 minutes to two hours after the injection of iron oxide and samples of the cerebral cortex were processed for electron microscopy by routine methods. In those animals that did not receive endotoxin, the colloidal iron was limited to the lumen of the cerebral capillaries and occasional large endothelial vacuoles. None of the iron was found in the endothelial pinocytotic vesicles. In the endotoxin animals the iron oxide particles were found in quantity in the capillary endothelium phagosomes, the basement membrane, and in astrocytes and their processes. The fine structure of the cerebral capillary is reviewed and evidence is presented in support of the hypothesis that the barrier mechanism for colloidal tracers lies in a unique property of the brain's endothelial pinocytotic vesicles.
The ultrastructural characterization of macroglial cell types
Authors: Wendell‐Smith C. P. , Blunt M. J. , Baldwin F. 
Published: January 2005

AbstractIn the prelaminar region of adult cat optic nerve, silver impregnation revealed a macroglial cell population consisting solely of small fibrous astrocytes. Electron microscopically the cells were characterized by abundant processes containing closely packed filaments and occasional glycogen granules; their perikarya contained few organelles, glycogen particles were conspicuous but not abundant, and their cytoplasmic and nucleoplasmic matrices were of low density.The laminar region contained typical fibrous astrocytes. These cells were characterized by similar processes and matrices but their perikarya contained filaments and were richer in organelles whose orientation was primarily radial.The postlaminar region contained both astrocytes and oligodendrocytes. The latter were identified as cells characterized by the absence of filaments and glycogen, the presence of canaliculi, dense cytoplasmic and nucleoplasmic matrices and perikarya very rich in organelles, whose orientation was primarily circumferential.The presence of filaments and/or glycogen on the one hand, and of dense matrices on the other hand, seemed to be mutually exclusive and provided diagnostic criteria for astrocytes and oligodendrocytes respectively. Bivalent forms were not seen. Cells usually identified as microglia were not seen.The relationship between astrocytes and finely myelinated nerve fibers in the lamina cribrosa indicates a sheath‐supporting role. Astrocytes are probably generally concerned with the isolation and insulation of neurons and their processes. Oligodendrocytes may be concerned with the energetic support of neurons and their processes.
A study of Golgi preparations from the dorsal lateral geniculate nucleus of the adult cat
Authors: Guillery R. W. 
Published: January 2005

AbstractFour cell types are distinguishable in the lateral geniculate nucleus. The largest (class 1) have their dendrites oriented in relation to the plane of the laminae. The dendrites cross laminar borders freely and bear many fine spines. Class 2 cells show less orientation of their dendrites. These dendrites bear clusters of grape‐like appendages close to the branching points and fine spines on their peripheral segments. Only the peripheral segments cross laminar borders. The smallest (class 3) cells have long stalked appendages and give rise to intrinsic axons which ramify close to the perikaryon. Cell classes 1 and 2 occur in laminae A and A1, with class 1 cells mainly concentrated between laminae. Class 3 cells occur in all major laminae. Class 4 cells, with long smooth dendrites oriented parallel to the lamina, lie in lamina B.Two types of extrinsic axon are seen. Type I axons give off many short simple terminal collaterals which often innervate more than one lamina. These are regarded as extra‐retinal afferents. Type II axons (probably retinal afferents) have complex flower‐like terminals and each axon innervates only one lamina.Contacts between several type II axons and two or more grape‐like clusters occur in laminae A and A1. In lamina B finer type II axons form complex overlapping terminal nests around the dendrites of class 4 cells.
Developmental and functional alterations in the fiber composition of the optic nerve in visually deprived mice
Authors: Gyllensten Lars , Malmfors Torbjörn , Norrlin‐Grettve Marie‐Louise 
Published: January 2005

AbstractDuring the first four months of postnatal life in mice, an increase occurred in the section area and number of fibers of the optic nerve, as recorded by phase contrast microscopy of epone‐embedded specimens. This was followed by a slight decrease for three months. A skew distribution of nerve fibers according to diameter was recorded, probably due to small groups of larger fibers.In mice reared in complete darkness for 2–4 months from birth, no significant differences were present in the fiber composition of the optic nerve, compared to corresponding normal controls. Slight retinal hypotrophy (decreased thickness and nuclear diameter) was found in dark‐reared animals.In adult mice, lack of visual stimulation (complete darkness from 4 to 7 months of age) caused an increase in number and diameter of the optic nerve fibers. No retinal hypotrophy was demonstrated in these animals.Judging by previous investigations, it is concluded from the present findings that growth of the fibers of the optic nerve is more independent of visual stimulation than is growth of the rest of the cells in the visual system. Point 3, as contrasted to point 2, implies that functional differences exist between apparently normal optic nerve fibers in dark‐reared mice and in controls, the former being unable to react to lack of activity by an increase in fiber size.
The development of hippocampal and dorsolateral pallial regions of the cerebral hemisphere in fetal rabbits. II. Twenty millimeter stage, neuroblast morphology
Authors: Stensaas Larry J. 
Published: January 2005

AbstractThe structure of the pallial region of the cerebral hemisphere of 20 mm rabbit embryos was studied with aniline and Golgi stains. The presence of a cortical plate distinguishes this stage from 15 mm embryos. It is a dense layer consisting of nerve cells which have migrated from the matrix lamina and represents the layer which will form most of the cerebral cortex. Golgi impregnations at this stage show that it consists largely of pyramidal cells whose apical dendrites ascend and branch in the marginal lamina.Neuroblasts in the matrix and intermediate laminae have distinctive morphology depending on their distance from the ventricular surface: (1) ascending axons arise from the round or elongated somata of cells in the matrix lamina, (2) horizontal axons and multiple short processes arise from neuroblast somata in the lower part of the intermediate lamina, and (3) descending axons originate from the inferior side of bipolar neuroblasts in the upper intermediate lamina. A single radial process, the preapex, arises from the other side. This sequence of changes suggests that neuroblast somata rotate around the axons as they migrate through the lower intermediate lamina and that new lengths of axons are “spun out” as neuroblasts become located at higher levels. It also raises the possibility that the preapex plays an active role in the process of migration.
Ascending projections of the lateral lemniscus in the cat and monkey
Authors: Goldberg Jay M. , Moore Robert Y. 
Published: January 2005

AbstractThe ascending connections of the lateral lemniscus were studied in the cat and squirrel monkey (Saimiri sciureus). In both species, the central nucleus of the inferior colliculus receives a massive projection from the lateral lemniscus. Only a few lemniscal fibers were found to terminate in the external nucleus of the inferior colliculus. The commissure of the lateral lemniscus originates from the dorsal nucleus of the lateral lemniscus and projects to the contralateral dorsal nucleus and the contralateral central nucleus of the inferior colliculus. No lemniscal fibers were seen ascending in the inferior brachium or terminating in the principal division of the medial geniculate body. A bundle of fibers was observed, however, which passed medial to the inferior brachium and terminated in the magnocellular or internal division of the medial geniculate. The bundle degenerated after lesions confined to the lateral lemniscus and is probably identical with the central acoustic tract of earlier workers. Evidence is presented that the fibers of the bundle are of spinal origin. Since the lemniscal fibers which ascend to the thalamus appear to be non‐auditory, it is suggested that the inferior colliculus is an obligatory relay station in the classical auditory system and that the inferior brachium is the only ascending pathway of the system to project upon the thalamus.