bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alterations in cerebellar germinal cell division induced by graft‐versus‐host disease
Authors: Griffin W. S. T. , Crom E. N. , Head J. R. 
Published: May 2005

AbstractA systemic immunological syndrome, graft‐versus‐host disease (GVHD), which does not cause inflammation or cell death in the cerebellum, is shown to retard granule cell production by decreasing the rate of DNA synthesis (S phase) and prolonging mitosis (M), at metaphase. The rate of cell production in diseased animals at postnatal day 14, quantitated by analysis of the rate of labeling of DNA with 3H‐thymidine (3H‐Tdr), revealed decreased ability to synthesize new DNA. The number of cells taking up 3H‐Tdr label per mm2, as detected by autoradiography, was similar in 14‐day‐old GVHD and control tissue as was the area of the germinal matrix zone and the number of mitotically active germinal cells per mm2 in sagittal sections near the midline. However, because the total volume of the cerebellum was less, the total number of mitotically active cells in the whole cerebellum of 11‐, 14‐, and 17‐day‐old diseased animals was less than in littermate controls. Furthermore, DNA synthesis per mitotically active germinal cell was less in diseased animals at each age examined. The mitotic index was unaffected until late in the disease (day 17), suggesting that a prolongation of the cell cycle was responsible for this GVHD‐induced decrease in DNA synthesis. Consistent with a prolongation of the cell cycle was the finding that the mitotic figures in 14‐day‐old GVHD cerebella were mostly metaphase figures, whereas those in control cerebella were, as predicted, mostly prophase. Prolongation of the cerebellar cell cycle in 11‐ and 14‐day‐old diseased animals may explain the dramatic decrease in the mitotic index, the thickness of the germinal matrix zone, and the number of germinal cells at postnatal day 17.
Rohon‐Beard cells in frog development: A study of temporal and spatial changes in a transient cell population
Authors: Eichler Victor B. , Porter Richard A. 
Published: May 2005

AbstractThe spatial distribution and temporal disappearance of Rohon‐Beard cells in the spinal cords of larval and newly metamorphosed Rana pipiens were studied histologically to provide a basis for further research dealing with this particular cell type. It was found that a maximum number of approximately 250 Rohon‐Beard neurons have differentiated within the spinal cord of Rana pipiens by larval stage I. The majority of these cells are located in the cephalic end of the spinal cord, with a large number found near the boundary of the anterior quarter and the second quarter of the spinal cord. Fewer cells are found in the third and fourth quarters.There is a gradual degeneration of these cells during larval life so that by stage XXV, which is the completion of the metamorphic climax, there are no normally appearing Rohn‐Beard cells present. Degeneration of the Rohon‐Beard cells does not progress cephalocaudally with development, but rather there appears to be a nearly equal proportional loss of Rohon‐Beard cells in each quarter of the spinal cord at each of the stages studied. All Rohon‐Beard cells present during larval development of Rana pipiens are located in a dorsal position, close to the midline. At all ages and in each quarter of the spinal cord there are no significant bilateral differences in number of these cells.
Target dependency of developing motoneurons in Xenopus laevis
Authors: Lamb Alan H. 
Published: May 2005

AbstractThe effect of complete and partial limb bud removal on motoneuron survival was studied in Xenopus laevis tadpoles. Amputation of both hind limb buds at stage 49 before limb innervation begins caused the subsequent death of all motoneurons. This result confirms that there are no exceptions to the rule that developing motoneurons must contact the limb to survive. Partial removals of the limb at early stages of innervation caused the subsequent death of motoneurons that normally project to the deleted segments while motoneurons for the remaining segments survived. Before dying, the motoneurons deprived of their normal targets invaded the remaining limb segments thereby forming erroneous projections. Since the motoneurons died despite contacting limb tissue, it is concluded that they must be dependent on contact with specific limb regions and that errors of projection lead to death. Since large‐scale errors of the type induced by this experiment affect only a minority of developing motoneurons in normal embryos, the possibility of small‐scale errors is discussed in an attempt to equate all naturally occurring motoneuron death with error correction.
The afferent and efferent organization of the lateral geniculo‐prestriate pathways in the macaque monkey
Authors: Benevento L. A. , Yoshida K. 
Published: May 2005

AbstractBoth anterograde (autoradiographic) and retrograde (horseradish peroxidase) tracing techniques were used to identify and characterize projections from the dorsal lateral geniculate nucleus (DLG) of the thalamus to the subdivisions of occipital prestriate cortex (generally defined by areas 18 and 19) in macaque monkeys. It was found that the DLG projects to area 19 and the anterior portion of area 18 located on the lateral, ventral, and ventromedial surfaces of the hemisphere. There is a general topographical organization such that the medial portion of the DLG projects to dorsal prestriate located between the lunate and superior temporal sulci, while the lateral portion of the DLG projects to ventral prestriate extending from the inferior occipitotemporal sulcus. In contrast DLG inputs to the lunate, superior temporal, and inferior occipital sulci are limited in extent, and involve only a portion of the bank or shoulder of each sulcus which is continuous with the cortex located on the surfaces of the surrounding preoccipital gyri. The projection to the inferior occipital sulcus is more extensive than the ones to the lunate and superior temporal sulci and involves the floor as well as the ventral bank. This means that there are certain functional subdivisions, such as those located within the lunate (eg, visual area 2) and superior temporal sulici which do not receive DLG input. Regardless of the location of these projections the terminal pattern was the same and occurred in horizontally segregated “patches” which were restricted to layer V and the lower, adjacent portion of layer IV. In contrast, the projections from the nearby pulvinar to cortical layers IV, III, and I of the same prestriate areas do not overlap with those from the DLG. An attempt was made to identify possible afferent inputs to these DLG‐prestriate paths. The HRP experiments reveal that the DL‐Gprestriate cells are concentrated in the DLG interlaminar zones and that their distribution overlaps the distribution of terminals from the superior colliculus and, as shown previously, prestriate cortex. Intraocular injections of radioactive precursors demonstrated transsynaptic transport to a number of structures except prestriate cortex. While the latter result does not prove that the DLG‐prestriate cells do not receive retinal input, one conclusion is that the DLG‐prestriate projection could be organized like pulvino‐prestriate systems which receive their inputs from the midbrain and cortex.
Cholinergic and catecholaminergic afferents to the olfactory bulb in the Hamster: A neuroanatomical, biochemical, and histochemical investigation
Authors: Macrides Foteos , Davis Barry J. , Youngs William M. , Nadi N. Suzan , Margolis Frank L. 
Published: May 2005

AbstractA series of neuroanatomical, biochemical, and histochemical studies have been conducted to determine the sources of cholinergic afferents to the main olfactory bulb (MOB) in the hamster. Following horseradish peroxidase (HRP) injections that are restricted to the MOB, retrograde neuronal labeling is observed bilaterally in the anterior olfactory nucleus, locus coeruleus, and raphe nuclei, and ipsilaterally in the ventral hippocampal rudiment, dorsal peduncular cortex, piriform cortex, nucleus of the lateral olfactory tract, anterior pole of the medial septal area and vertical limb of the diagonal band, nucleus of the horizontal limb of the diagonal band (HDB), and hypothalamus. Spread of HRP into the accessory olfactory bulb results in additional neuronal labeling ipsilaterally in the bed nucleus of the accessory olfactory tract, medial amygdaloid nucleus, and bed nucleus of the stria terminalis, and bilaterally in the posteromedial cortical amygdaloid nucleus. Retrograde tracing studies also have been conducted in cases with lesions in the basal forebrain or hypothalamus to assess the extent to which such lesions interrupt fibers of passage from other sources of centrifugal afferents, and the effects of such lesions on choline acetyltransferase (CAT) activity and catecholamine content in the MOB and on acetylcholinesterase (AChE) activity in the forebrain have been evaluated. Lesions in the basal forebrain reduce or eliminate CAT and AChE activity in the MOB in direct relationship to the extent of damage to the HDB. Norepinephrine (NE) content in the MOB also is reduced by basal forebrain lesions, but in relationship to damage of the medial forebrain bundle (MFB). The hypothalamic lesions have no effect on AChE activity in the forebrain or on CAT activity in the MOB, but they eliminate retrograde labeling in the locus coeruleus and raphe nuclei and reduce the NE content of the MOB to undetectable levels. The dopamine content of the MOB is not reduced by any of the lesions. Anterograde tracing studies have been conducted to compare the rostral projection patterns of the HDB with the distribution of AChE activity. Most of the rostrally directed axons travel in association with the MFB. A small component of axons travels in association with the lateral olfactory tract. Within the MOB, the axons terminate predominantly in the glomerular layer and in the vicinity of the internal plexiform layer. The projection and termination patterns of the HDB correspond well with the distribution of AChE activity. These various results indicate that the HDB is the major source of cholinergic afferents to the MOB.
Plasticity in a central nervous pathway in Xenopus: Anatomical changes in the isthmotectal projection after larval eye rotation
Authors: Udin Susan B. , Keating Michael J. 
Published: May 2005

AbstractIn this paper we present evidence that early eye rotation in Xenopus leads to anatomical rearrangements in a portion of the binocular visual system. In the past, electrophysiological mapping had shown that the topography of the ipsilateral visuotectal projection is changed by such eye rotation and that this change requires visual experience. However, knowledge of the anatomical basis for this electrophysiological change was lacking. The identification of the nucleus isthmi as a link in the projection has allowed us to study the topography of the ipsilateral system by use of horseradish peroxidase. We present data showing that early eye rotation alters the topography of the crossed isthmotectal projection. These results demonstrate that the orientation of a topographically organized projection can be changed by procedures which do not involve direct manipulation of the source, pathway, or target of the projection.
The accessory optic system of Rana pipiens: Neuroanatomical connections and intrinsic organization
Authors: Montgomery Neil , Fite Katherine V. , Bengston Lynn 
Published: May 2005

AbstractThe accessory optic system of Rana pipiens was investigated by autoradiographic, horseradish peroxidase, and Golgi techniques, revealing a complexity of neuroanatomical organization previously unrecognized. Retinal afferents project to the nucleus of the basal optic root (nBOR) via a primary bundle and more diffuse, medial bundle of optic axons, both of which contain large‐ and small‐diameter fibers. At least six types of retinal ganglion cell contribute to the basal optic root (BOR), including giant ganglion cells, two intermediate‐sized ganglion cell types, small ganglion cells, and two types of displaced ganglion cell. The major retinal projection is contralateral, but a small, ipsilateral component also exists. Afferents from neurons which are postsynaptic to the thalamic retinal terminal fields also reach nBOR.Four distinct cell types were identified within the terminal field of nBOR: stellate neurons (63%), amacrine cells (19%), elongate neurons (14%), and large ganglionic neurons (4%). Both stellate and amacrine cells appear to be intrinsic neurons, while elongate and ganglionic neurons constitute the efferent neuron population of nBOR. In addition, cells which lie medial to the terminal field, pyriform and commissural neurons, send dendrites into nBOR. Pyriform neurons project to the nucleus of the medial longitudinal fasciculus (nMLF) and cranial nerve nuclei III and IV, while commissural neurons project to the contralateral nBOR. Large reticular neurons of the nMLF also send dendrites into nBOR.Efferent projections from nBOR were observed in the large‐celled pretectal nucleus and in nucleus lateralis profundus. A second major projection originates from the peri‐nBOR region and is associated with the oculomotor system and with the nMLF. Efferent projections from the nMLF to the vestibular nuclei and to the rostral spinal cord were also observed, as well as projections which reach the brainstem from the large‐celled pretectal nucleus, the posterior thalamic and anterior mesencephalic central gray.
The central projections of trigeminal primary afferent neurons in the cat as determined by the tranganglionic transport of horseradish peroxidase
Authors: Marfurt Carl F. 
Published: May 2005

AbstractThe central projections of five peripheral branches of the trigeminal nerve were investigated by the method of transganglionic transport of horseradish peroxidase (HRP). In separate animals, the corneal, supraorbital, infraorbital, mental, or inferior alveolar branches were transected and soaked in concentrated solutions of HRP. Forty‐eight to 72 hours after surgery, the brainstem, upper cervical spinal cord, and trigeminal ganglia were perfusion‐fixed and processed according to the tetramethylbenzidine technique. The results show that trigeminal primary afferent neurons which innervate the cornea project mainly to the levels of caudal pars interpolaris and caudal pars caudalis. In contrast, trigeminal primary afferent neurons whose peripheral processes course through the supraorbital, infraorbital, or mental nerves project most heavily to the trigeminal main sensory nucleus, pars interpolaris, and the rostrocaudal middle three‐fifths of pars caudalis. Trigeminal primary afferent neurons which give origin to the inferior alveolar nerve project heavily and in approximately equal numbers of all rostrocaudal levels of the trigeminal brainstem nuclear complex (TBNC). A small number of fibers from each of the latter four cell populations project directly to the contralateral C1‐C2 dorsal horn. A small number of fibers from each cell population studied end in the reticular formation immediately adjacent to the spinal nucleus of V. It is concluded that the cornea and facial skin regions of the cat are represented nonuniformly along the rostrocaudal length of the TBNC.
Efferent systems of the rabbit visual cortex: Laminar distribution of the cells of origin, axonal conduction velocities, and identification of axonal branches
Authors: Swadlow Harvey A. , Weyand Theodore G. 
Published: May 2005

AbstractSeveral efferent systems of visual area I in Dutch rabbits were studied with anatomical (horseradish peroxidase) and physiological (antidromic) methods. Anatomical studies provided information regarding the laminar origin of the projections to the contralateral hemisphere, visual area II, the dorsal lateral geniculate nucleus, and the superior colliculus. Physiological studies provided information regarding conduction velocities and multiple destinations of efferent axons. Both the callosal projection and the projection to V‐II were shown to originate primarily in layer II‐III. However, approximately 10‐20% of the callosal projection and 20–40% of the projection to V‐II originated in layers IV and V. In contrast, the projection to the dorsal lateral geniculate nucleus originated nearly exclusively in layer VI, while corticotectal neurons occurred primarily in layer V. A significant number of corticotectal neurons were, however, found in layer IV. Thus, the above efferent systems were found to differ in their principal laminar origin and in the diffuseness of that origin. The origins of corticocortical projections were considerably more diffuse than those of corticofugal projections.In addition to differences in laminar origin, efferent systems also differed significantly in the conduction velocities of their axons. The projection to visual area II and to the lateral geniculate nucleus consisted primarily of very slowly conducting axons, while the projection to the superior colliculus was fast conducting. The callosal projection consisted of both slow and fast conducting axons. Finally, the question of branching of V‐I efferent axons was addressed. Although the laminar origin of the projections to the contralateral hemisphere and to visual area II overlapped considerably, none of these corticocortical axons could be shown to project to both locations or to a subcortical destination. In contrast, approximately one‐third of corticotectal axons were shown to project a collateral into the thalamus. Although the destination of this collateral is unclear, it is medial to the lateral geniculate nucleus and may be the pulvinar.
Uptake and localization of 3H‐2 deoxy‐D‐glucose by retinal photoreceptors
Authors: Witkovsky Paul , Yang Chen‐Yu 
Published: May 2005

AbstractFollowing dark incubation of isolated retinas of Xenopus laevis in Ringer solution supplemented with 3H‐2 Deoxy‐D‐glucose (2DG), virtually all of the uptake of the label was by the inner segments and synaptic bases of the photoreceptor cells. Autoradiographs prepared from conventionally fixed tissue showed the same cellular distribution of label as those prepared from identically incubated, unfixed, freeze‐dried retinas. However, fixation removed about 77% of the total counts. This fixation‐labile, soluble fraction was identified as being primarily 2DG‐6 phosphate by thin‐layer chromatography. The remaining insoluble fraction corresponded in distribution to glycogen grains. In cones, glycogen is stored primarily in the paraboloid, whereas in rods it is distributed throughout the inner segment and synaptic base. EM autoradiographs illustrated that these were the sites over which fixationresistant 2DG label was localized. Measurements of radioactivity associated with extracts of retinal glycogen following 2DG incubation demonstrated that a disproportionately high fraction of total counts were associated with the glycogen fraction. We conclude that in the amphibian retina 2DG may be incorporated into glycogen.
The organization of binocular cortex in the primary visual area of the rabbit
Authors: Hughes A. , Vaney David I. 
Published: May 2005

AbstractA conscious rabbit which crouches in the ‘freeze’ position has an unequivocal 24° wide binocular field formed by the overlap of the two 12° sectors of uniocular optical field which extend nasal of its midline. Although this investigation reveals that the horizontal representation of the uniocular visual field in cortical visual area I extends more nasal than in earlier reports, it is found to terminate at the midline when the eyes are set in the standard freeze position. The 12° sectors of uniocular field nasal of the midline were not represented in spite of being served by retina. The binocular field of the rabbit in the freeze posture thus appears to have no binocular representation in visual area I.Nevertheless, the presence of a binocular region was confirmed in rabbit visual area I but the projections to it, via the contralateral and ipsilateral eyes, deal with the nonoverlapping sectors of monocular field when the eyes are in the freeze position. The maps of the visual field obtained in one hemisphere via the contralateral and ipsilateral projections were subject to a horizontal divergent disparity of some 18°. The presence of binocular single units in these regions was also confirmed but their two receptive fields were necessarily located in different visual hemispheres and again subject to an 18° mean horizontal divergent disparity. They could not be simultaneously stimulated by any localized feature of an object and are thus precluded from involvement in binocular single vision during the freeze position.The systematic, rather than reportedly random, topography of the ipsilateral projection to visual area I ensured that it could be well fused with the similarly organized contralateral projection by means of an 18° vergence of the eyes from the freeze position. The horizontal receptive field disparity of binocular single units is then brought to a zero mean value which enables their receptive fields through each eye to be simultaneously stimulated by the same part of an image. Tested units then evinced response summation; a minimum requirement for binocular vision. In this equivalent primary position of the eyes, the entire binocular visual field is completely represented in visual area one of both hemispheres.The rabbit thus appears to employ a two‐state cortical system for forward vision. In the freeze position the visual field attains a cyclopean extent of 360° but the receptive fields of cortical binocular units are widely divergent. The classic binocular optical field may then project to some other region of brain which subserves binocular vision. Upon examination of a frontal object the animal must verge its eyes in order to obtain binocular single vision in visual area I; it then temporarily surrenders part of its rear visual field. An explanation in terms of ocular image quality is suggested.