bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topographical localization in the olivo‐cerebellar projection: An electrophysiological study in the cat
Authors: Armstrong D. M. , Harvey R. J. , Schild Renée F. 
Published: January 2005

AbstractMicro‐electrodes have been used to record the antidromic responses generated in olivary neurones by electrical stimulation of their axon terminations in the cerebellar cortex. This electrophysiological technique, in combination with precise histological methods for locating postions of the micro‐electrode tip, has been used to reinvestigate the topography of much of the olivo‐cerebellar projection. The results are partly in accord and partly in conflict with those of earlier investigations in which purely anatomical techniques were employed. In general, the terminations of a circumscribed group of olivary neurones have been found to be located within a longitudinal strip of the cerebellar cortex. Such strips frequently ignore the anatomical landmarks which divide the cerebellar cortex into lobules. The axons of a number of individual olivary neurones have been found to branch to provide a termination in both the anterior and the posterior lobe of the cerebellum. It was also found that olivary neurones projecting to a particular area of cerebellar cortex were in some cases situated in neighbouring regions of more than one of the main anatomical subdivisions of the olive (principal olive and medial and dorsal accessory olives). The discrepancies between the present findings and those made earlier are discussed.
The adrenergic innervation of the rat thalamus as revealed by the glyoxylic acid fluorescence method
Authors: Lindvall Olle , Björklund Anders , Nobin Anders , Stenevi Ulf 
Published: January 2005

AbstractThe adrenergic innervation of the thalamus, epithalamus, metathalamus, and subthalamus in the rat has been investigated by means of the recently introduced glyoxylic acid fluorescence method. Many areas of the thalamus and adjoining regions, that appear sparsely innervated by catecholamine (CA) fibers in specimens processed according to the standard Falck‐Hillarp formaldehyde method, were found to be richly supplied with such fibres in the glyoxylic acid‐treated specimens. Moreover, the glyoxylic acid method allows the tracing of the CA axons from the cell bodies up to the terminals, and in combination with stereotaxic lesions the following CA systems to the thalamus could be established:
The locus coeruleus system. Most of these axons ascend in the so‐called dorsal tegmental bundle through the mesencephalon and the zona incerta into the medial forebrain bundle. From this bundle branches were traced along several routes, giving rise to extensive terminal systems in many thalamic, metathalamic and pretectal areas, most notably the anterior, ventral and lateral nuclear complexes, and the medial and lateral geniculate bodies.
The dorsal periventricular bundle, which constitutes a previously not described adrenergic component of the dorsal longitudinal fasciculus. This system originates in cell bodies (defined as the A11 cell group) in the dorsal raphe region, the central gray of the mesencephalon, and in the periventricular gray of the caudal thalamus. The axons ascend within the dorsal longitudinal fasciculus and give rise to a thalamic and hypothalamic periventricular system, projecting to medial and midline thalamic, epithalamic and pretectal regions.
Part of the terminals in the paraventricular thalamic nucleus was identified with a non‐locus projection from cell bodies in the pontine or medullary reticular formation.
A system of delicate, probably dopamine‐containing axons was revealed in the caudal thalamus, the zona incerta and the dorsal and anterior hypothalamus. This system probably originates in the dopamine cell bodies of the diencephalic A11 and A13 cell groups, forming a hitherto unknown intradiencephalic dopaminergic system.
The adrenergic afferent systems to the thalamus can, to a large extent, be regarded as adrenergic components of known ascending reticular projections. The information on the adrenergic systems obtained with the glyoxylic acid method revealed new features of the organization of the thalamic projections from the brain stem reticular formation.
Retrograde axonal transport and the demonstration of non‐specific projections to the cerebral cortex and striatum from thalamic intralaminar nuclei in the rat, cat and monkey
Authors: Jones E. G. , Leavitt Randi Y. 
Published: January 2005

AbstractThe intralaminar nuclei of the thalamus have been examined particularly in the rat but with additional observations in the cat and squirrel monkey, with a view to determining the extent of their connections with the cerebral cortex and/or striatum. Cells in the intralaminar and other thalamic nuclei were labeled by retrograde axonal transport of the enzyme, horseradish peroxidase, from injection sites of varying size in the cerebral cortex and striatum.This system provides a useful means of determining certain parameters of the horseradish peroxidase technique. It is concluded that the degree of retrograde labeling of a cell is primarily dependent upon the number and concentration of its axon terminals in the vicinity of the injection site. Injections of the striatum in the rat and monkey cause intense labeling of many cells in the intralaminar nuclei. Conversely, injections in the medial, frontal and parietal cortex of all three species, though leading to heavy labeling of many cells in the appropriate thalamic relay nuclei, result in only light labeling of relatively few cells in the intralaminar nuclei. Cells in a single intralaminar nucleus, however, though showing a broad topographical relationship, can be labeled from quite wide areas of the cerebral cortex. These results are consistent with the view that the intralaminar nuclei (including the parafascicular and centre médian) project densely to the striatum and sparsely and diffusely upon the cerebral cortex.
Differences in membrane structure between excitatory and inhibitory synapses in the cerebellar cortex
Authors: Landis Dennis M. D. , Reese T. S. 
Published: January 2005

AbstractSeveral synapses of known physiological action are antomically segregated in the cerebellar cortex and are readily identified in freeze‐fracture preparations. Excitatory synapses, such as the parallel fiber‐to‐Purkinje spine synapse, climbing fiber‐to‐Purkinje spine synapse, and mossy or climbing fiber‐to‐granule cell dendrite synapse, were characterized by small aggregates of large particles on the cytoplasmic half of the presynaptic membrane, by a distinctly widened synaptic cleft, and by a large aggregate of particles on the external half of the postsynaptic membrane. Inhibitory synapses, such as the stellate cell axon‐to‐Purkinje dendrite synapse and the basket cell axon‐to‐Purkinje soma synapse, had no comparable specialization of either the pre‐ and postsynaptic membrane. The striking contrast in membrane structure at excitatory and inhibitory synaptic contacts presumably reflects differences in either the composition or organization of membrane proteins integral to synaptic function. Puncta adhaerentia between granule cell dendrites in cerebellar glomeruli were characterized by particles aggregated on the external half of both apposed membranes and were further differentiated from synaptic contacts by the smaller size of the particles. Protuberances on the external half of the presynaptic membrane were either small and coextensive with the synaptic contact or were larger and surrounded it; it is suggested that the small protuberances are synaptic vesicle sites whereas the large ones are coated vesicle sites.
Arachnoid villi in the spinal cord of dasyurid marsupials
Authors: Attwood H. D. , Wooley Patricia A. 
Published: January 2005

AbstractDuring a routine histopathological study of dasyurid marsupials a high incidence of meningo‐encephalo‐myelitis due to Toxoplasma gondii was found. Decalcified blocks of the vertebral columns contained nodules closely related to the nerve roots and projecting into the venous sinuses. At first, these nodules were considered to be granulomata, but further studies revealed a constant relationship to the anterior nerve roots, a frequency of bilateral symmetry and an organoid structure which were more in keeping with a physiological rather than a pathological structure. These structures were morphologically similar to arachnoid villi in the head of dasyurid marsupials and were confined to the lumbo‐sacral cord. It is suggested that they are spinal arachnoid villi and that their varying cellularity results from the associated Toxoplasma infection.
Specification of retinal central connections in Rana pipiens before the appearance of the first post‐mitotic ganglion cells
Authors: Sharma S. C. , Hollyfield Joe G. 
Published: January 2005

AbstractThe order of production of retinal cells and the time when retinal cells become post‐mitotic was studied in Rana pipiens embryos using 3H‐thymidine autoradiography. Cell division stops first in the fundus of the retinal rudiment between embryonic stages 17 and 18 and gradually becomes restricted to the retinal margin. The ganglion cells in the fundus are among the first cells to become post‐mitotic.The specification of the central connections of ganglion cells was studied by rotating the eye primordium at embryonic stages 16–21. After metamorphosis, the visual projection from the rotated eye to the contralateral optic tectum was mapped electrophysiologically and compared with the normal retinotectal map. In all cases, the visual projection map was rotated through the same angle as was indicated by the position of the choroidal fissure. It appears that ganglion cell connections with the tectum were specified by stage 17. These results indicate that ganglion cell central connections are specified before the first ganglion cells become post‐mitotic.
Synaptogenesis in the photoreceptor terminal of the mouse retina
Authors: Blanks Janet C. , Adinolfi Anthony M. , Lolley Richard N. 
Published: January 2005

AbstractObservations are presented of a combined light and electron microscopic study of synaptogenesis in the photoreceptor terminal of visuallycompetent mice. Our study suggests that photoreceptor synaptogenesis in these retina progresses through a sequence of postnatal changes which leads to the ordered arrangement of processes within the adult photoreceptor terminal. On the 5th postnatal day, neuronal processes from synaptic contacts with a photoreceptor terminal, usually in the vicinity of a synaptic ribbon. Following the formation of synaptic contacts, the processes invaginate into the photoreceptor terminal, maintaining their position, lateral to a synaptic ribbon. Beginning on about the 10th day, a central process enters the terminal to yield a triad configuration which is a characteristic of a mature photoreceptor terminal. The formation of triads is essentially complete by the 14th postnatal day.Our observations suggest that horizontal cell processes form synaptic contacts with the photoreceptor terminal before bipolar cell dendrites, implying that the horizontal cells mature in advance of the bipolar cells. This possibility is discussed in terms of the appearance of the electroretinogram (ERG) in the developing mouse retina.
Some observations on the early development of the optic tectum in the frog (Rana pipiens), with special reference to the effects of early eye removal on mitotic activity in the larval tectum
Authors: Currie Julia , Cowan W. M. 
Published: January 2005

AbstractFollowing unilateral eye removal in Rana pipiens at embryonic stages 21–24 there is a statistically significant reduction in the numbers of mitoses found in the contralateral optic tectum at larval stage XIV amounting to approximately 16 per cent. Most of the reduction in mitotic activity occurs in the rostral third of the tectum and does not appear to involve its caudal pole, where cell proliferation is most vigorous. Since thymidine autoradiography indicates that the majority (if not all) of the cells being generated in the rostral third of the tectum at stage XIV are either glial or ependymal cells, it is suggested that the primary effect of eye removal on cell proliferation in the tectum is upon gliogenesis. Using the autoradiographic method for tracing axonal connections, it has been found that the axons of the retinal ganglion cells reach the tectum by embryonic stage 22, and by larval stage XIV have spread to all but its caudomedial region.
Connections of the median and dorsal raphe nuclei in the rat: An autoradiographic and degeneration study
Authors: Conrad Lily C. A. , Leonard Christiana M. , Pfaff Donald W. 
Published: January 2005

AbstractAscending and descending projections from the median and dorsal raphe nuclei of the midbrain were mapped in the albino rat, using reduced‐silver stains after lesions or the autoradiographic technique following injections of tritiated proline. In all major respects the two techniques gave the same results. The majority of the ascending projections sweep ventrally from the raphe nuclei, then curve rostrally to course through the ventral tegmentum and into the medial forebrain bundle (MFB). Others radiate through the mesencephalic reticular formation (RF) and central grey, turning ventrally at the posterior thalamic border to enter the subthalamus. From the MFB, fibers branch into the hypothalamus, preoptic areas, anterior amygdala and olfactory tubercle, while some fibers enter the fornix or the stria terminalis. Many fibers continue rostrally in the MFB, joining the diagonal bands of Broca to reach the septal nuclei or, further rostrally, the cingulum bundle. Fibers in the cingulum bundle turn caudally around the genu of the corpus callosum, some branching into the cell‐free layers of the pregenual cortex. Runing caudally, then curving around the splenium, the cingulum bundle projection sprays out into the subiculum and in some cases a projection into the hippocampus is seen.Other ascending projections include one to the habenular nuclei through the fasciculus retroflexus. Projections to the mediodorsal, parafascicular and reuniens nuclei of the thalamus were also noted.Descending projections were observed to the dorsal tegmental nucleus and locus coeruleus and diffusely to the pontine reticular formation and caudal central grey. No projections were seen below the level of the facial nerve nucleus and none were observed to the cerebellum, caudal raphe nuclei or cranial nerve nuclei.
The localization of 5‐hydroxytryptamine in chromaffin cells of the leech body wall
Authors: Coggeshall Richard E. , Yaksta‐Sauerland Barbara A. 
Published: January 2005

AbstractThe present study is an analysis of the sites of uptake of radioactive 5‐HT into the leech body wall. Two sites of uptake are noted: (1) the axons and nerve terminals containing large dense core vesicles and (2) the type I cells of the vasofibrous tissue. Both of these cell types are chromaffin cells in that they contain vesicles or granules with cores that reduce dichromate salts. Chemicla analysis indicates that most of the radioactivity in the body wall at the time of sacrifice is 5‐HT. Thus, these two cell types acquire 5‐HT when it is present in the extracellular environment and presumably store it in the cores of the vesicles of granules that characterize these cells. This acquisition of 5‐HT may be an impotrant method of inactivation for 5‐HT.In addition, the fine structure of the vasofibrous tissues is described here for the first time. There are two types of cells in the vasofibrous tissue, rather than one as previously thought, and the electorn microscope clearly shows that the fibrils of vasofibrous tissue are not pigmented capillaries.
Time of neuron origin in preoptic and septal areas of the mouse: An autoradiographic study
Authors: Creps Elaine S. 
Published: January 2005

AbstractTimes of neuron origin were determined for septal and preoptic nuclei of adult mice given a single injection of H3‐thymidine at some stage of development. In the septal area, the sequence of neuron origin for its constituent nuclei roughly follows phylogenetic trends. Mediolateral and lateromedial gradients in septal and preoptic areas, respectively, seem to be opposites but are both “outside‐in,” as is a rostrocaudal septal gradient when viewed sagittally. An “inside‐out” gradient characterizes the olfactory tubercle and possibly the periventricular proptic region. These findings strengthen the impression that cells of nuclear areas undergo final division in an “outside‐in” sequence; those of layered structures arise “inside‐out.” A dorsoventral gradient in periventricular preoptic region parallels that in hypothalamus. The significance of these gradients is unknown, but they often presage corresponding gradients in nuclear differentiation, as in the preoptic area.Cell birthdates for nucleus accumbens resemble those in the striatum more than in the septum, where the nucleus is usually catalogued. To help resolve the issue of whether the preoptic area is telencephalic or diencephalic, it was compared with neighboring regions. No conclusions were reached, since similarities exist in both directions. The validity of a telodiencephalic boundary based on cytoarchitectonics. circuitry, or function is considered; such separation of the forebrain, except for topographical convenience, appears unwarranted.
Restitution of function and collateral sprouting in the cat spinal cord: The partially hemisected animal
Authors: Murray Marion , Goldberger Michael E. 
Published: January 2005

AbstractThe hypothesis that collateral sprouting might be correlated with recovery of function was tested by a combination of behavioral and anatomical studies. Partial hemisections, sparing the dorsal columns, were made between T12 and L1 of cat spinal cord. Initially, all reflex and locomotor hindlimb activity was depressed ipsilaterally. During two postoperative weeks behavioral and electromyographic responses increased in response to intrinsic reflex elicitation but not to descending or crossed reflex elicitation. Marked improvement in use of the limb occurred as intrinsic reflex activity increased and became, in some cases, hyperactive. The status then remained stable for ten months. Since intrinsic reflexes are mediated by ipsilateral dorsal roots, the intraspinal distribution of L5 or L6 dorsal roots was determined by degeneration methods ten months after hemisection or by quantitative radioautography 20 days after hemisection. By both methods, the dorsal root distribution was found to be asymmetrical in the spinal gray. It was greater on the experimental side and the distribution was altered, having a greater distribution medially in Rexed's lamina VI and laterally in lamina VII. These anatomical changes are considered as signs of collateral sprouting from dorsal roots in response to degeneration of descending tracts on the same side. Dorsal root distribution to dorsal horn (laminae I–IV), motor nuclei, and nucleus gracilis is symmetrical. Regions of increased and of expanded dorsal root input can be correlated with electrophysiologically determined location of interneurons in the path of cutaneous reflexes and of stretch reflex facilitation. Behavioral and anatomical changes were selective; intrinsic reflexes recovered or became hyperactive and ipsilateral dorsal roots showed evidence of collateral sprouting during the recovery period, although a causal relationship between the two cannot be proven, by the present experiments.
Restitution of function and collateral sprouting in the cat spinal cord: The deafferented animal
Authors: Goldberger Michael E. , Murray Marion 
Published: January 2005

AbstractUnilateral hindlimb deafferentation is followed initially by generalized loss of all reflex and useful function. As useful movement returns, certain descending reflexes recover and become hyperactive: crossed reflexes do not. Recovery of movement and reflex hyperactivity are then abolished by subsequent destruction of the ipsilateral descending systems. Although there is no sprouting from contralateral dorsal roots, bilateral degeneration of descending systems is asymmetrical, being greater in density and distribution on the previously deafferented side. Collateral sprouting to certain spinal laminae apparently took place during the recovery period from the same source which mediated reflex hyperactivity; the ipsilateral descending systems. A substantial descending projection to Clarke's nucleus was found only on the experimental side, however, suggesting that a central feedback system replaced the abolished peripheral feedback. If functional, this might subserve recovery of the ability to maintain a limb position.Chronically deafferented cats which are then transected show, for the first time, hyperreflexia of crossed responses, which develops gradually during the first week post‐transection. It may be related to sprouting of contralateral dorsal roots for contralateral ganglion injection with 3H‐proline gives a larger than normal ipsilateral distribution of grain density over the commissural nuclei.It is suggested that recovery and hyperactivity of reflex responses underlie the recovery of useful movement and that reflex recovery may be related to collateral sprouting. It is also suggested that both the reflex and the anatomical response to a given lesion is restricted to only one of the remaining systems and is therefore a specific rather than a generalized response.
Hippocampal development in the rat: Cytogenesis and morphogenesis examined with autoradiography and low‐level X‐irradiation
Authors: Bayer Shirley A. , Altman Joseph 
Published: January 2005

AbstractThe cytogenesis and morphogenesis of the rat hippocampus was examined with the techniques of 3H‐thymidine autoradiography, cell pyknosis produced by low‐level X‐irradiation, and quantitative histology.The procedure of progressively delayed cumulative labelling was used for autoradiography. Groups of rats were injected with four successive daily doses of 3H‐thymidine during non‐overlapping periods ranging from birth to day 19. They were killed at 60 days of age, and the percentage of labelled cells was determined. The pyramidal cells of Ammon's horn and the polymorph cells of the dentate gyrus are not labelled postnatally, confirming earlier conclusions of their prenatal origin. In the dentate gyrus, 85% of the granule cells are formed postnatally, with 45% forming during the first week. The majority of the small cells of the dentate molecular layer and of the Ammonic strata oriens, radiatum, and lacunosum‐moleculare are formed during the second week.As an aid to locating the proliferative compartments of the hippocampus during development and to characterize the time course of both cell differentiation and morphological development, rats ranging in age from gestation day 17 to postnatal day 103 were killed six hours after one exposure to 200r X‐rays, and the pyknotic cells were counted. Cell pyknosis in Ammon's horn reaches a maximal level prenatally and declines rapidly during the early postnatal period. Cell pyknosis in the dentate gyrus reaches its highest level during the second postnatal week and declines gradually with some radiosensitive cells still present in the adult. Immature granule cells are also at their highest level during the second postnatal week, while mature granule cells gradually accumulate to attain asymptotic levels at around two months of age. The alignment of the pyramidal cells to form the characteristic curvature of Ammon's horn occurs shortly after pyramidal cell cytogenesis is completed. Conversely, the sharp fold in the dentate gyrus is apparent from the day of birth onward, before the completion of granule cell cytogenesis. Possible mechanisms for the morphological development of the dentate gyrus along with a consideration of the possible migratory route of granule cell precursors is also discussed.