bluuebunny/crossref_metadata_2025_split huggingface dataset:
Afferent synaptic connections between hair cells and the somata of intramacular neurons in the gravity receptor system of the statocyst of octopus vulgaris
Authors: Colmers William F. 
Published: January 2005

AbstractIn the sensory epithelium (macula) of the gravity receptor system of the statocyst of Octopus vulgaris, there are two types of afferent neurons, distinguished according to their position in the epithelium. The somata of one type lie accumulated in a ring peripheral to the hair cell layer of the epithelium; these are disignated as perimacular neurons. The somata of the other type lie among the hair cells, below the level of their nuclei; these are designated as intramacular neurons. Axons of afferent neurons which touch the hair cells are postsynaptic to some of the hair cells touched. As the somata of the intramacular neurons also touch the hair cells, they were investigated by serial electron microscopic reconstruction to determine if afferent synaptic contacts between hair cells and these somata occur.An average of about 600 intramacular neurons was counted in two maculae. Afferent synapses were seen to occur between hair cells and the somata of 76% of the intramacular neurons investigated. The postsynaptic processes of the intramacular neurons' somata were of two morphological types; one with a finger‐like and one with a flat postsynaptic process (average of one synapse of each type per soma). The soma of an intramacular neuron can be postsynaptic to more than one hair cell simultaneously (average of 1–2 hair cells per soma). In addition to being presynaptic to only one neuron's soma, a hair cell could be simultaneously presynaptic to the axons of one or more afferent neurons. The morphological findings are discussed as to their possible physiological consequences.
Expansion of the ipsilateral visual corticotectal projection in hamsters subjected to partial lesions of the visual cortex during infancy: Anatomical experiments
Authors: Rhoades Robert W. 
Published: January 2005

AbstractElectrophysiological methods were employed to determine whether or not partial visual cortical lesions in neonatal (7–11‐day) hamsters produced large scotomas in the cortical visual representation. In cases where such scotomas were present electrophoretic deposits of radioactive amino acids in the visually responsive “cortical remnant” of the damaged hemisphere resulted in labeling throughout the lower portion of the stratum griseum superficiale and the stratum opticum of the ipsilateral superior colliculus. No differential labeling of the part of the colliculus which was topographically matched with the remaining visual representation in the cortical remnant was observed. In normal hamsters relatively localized, visual cortical deposits of radioactive amino acids resulted in superficial layer labeling only in portions of the colliculus which corresponded to the locus of the cortical deposit.In a similar fashion, small lesions at physiologically defined loci in the cortical remnant produced degeneration throughout most of the superficial tectal laminae, but a more restricted “focus” of denser degeneration was also visible in these cases. The position of this focus in the colliculus for a given cortical lesion varied with the nature of the visual map in the cortical remnant. In several additional neonatally brain‐damaged hamsters large lesions of the visual cortex in the intact hemisphere were combined with radioactive amino acid deposits in the cortical remnant to determine whether or not axons from the crossed corticocollicular pathway previously demonstrated in such hamsters were intermingled with fibers from the ipsilateral corticotectal projection. In alternate sections processed for autoradiography or by the Fink‐Heimer ('67) method autoradiographic label and degeneration argyrophilia were both observed in the medial part of the colliculus ipsilateral to the neonatal cortical lesion.
Expansion of the ipsilateral visual corticotectal projection in hamsters subjected to partial lesions of the visual cortex during infancy: Electrophysiological experiments
Authors: Rhoades Robert W. 
Published: January 2005

AbstractSingle unit recording from cells in the superior colliculus ipsilateral to the damaged hemisphere in hamsters subjected to unilateral removal of a part of the posterior neocortex during infancy was combined with electrical stimulation of the cortical remnant and the visual cortex in the undamaged hemisphere. Cells activated by stimulation of the cortical remnant were recorded in all portions of the colliculus. No differences in percentages of driven cells or threshold current intensities were noted between electrode penetrations in which collicular neurons having receptive fields within the remaining visual cortical representation were recorded and tracks where units with receptive fields outside this region were isolated. In the medial part of the tectum ipsilateral to the damaged hemisphere cells driven by stimulation of either cortex were encountered. It was also demonstrated that stimulation of the ipsilateral cortical remnant and/or the contralateral cortex was capable of suppressing discharges normally elicited by optic chiasm or visual stimulation in a manner qualitatively similar to that observed for collicular cells in normal hamsters. The response properties of cells functionally influenced by the ipsilateral and/or contralateral corticles were not different from those of neurons which received no demonstrable cortical input. The receptive field characteristics of the sample of neurons recorded were, on the whole, quite similar to those of collicular neurons in hamsters subjected to lesions of the visual cortex as adults.
An electron microscopic study of the afferent connections of the lateral reticular nucleus of the cat
Authors: Hrycyshyn A. W. , Flumerfelt B. A. 
Published: January 2005

AbstractThe mode and pattern of termination of the afferents to the lateral reticular nucleus (LRN) of the cat were examined at the cellular level through the ultrastructural localization of induced degeneration. Examination of the LRN following hemicordotomy at the fifth and sixth cervical levels revealed that most of the degenerating terminals were in contact with intermediate and distal dendrites, and that most of these degenerating terminals were small and contained round vesicles. Fewer degenerating terminals were observed on the somata and proximal dendrites after spinal hemisection, and most of these terminals were large and contained round vesicles. Following lesions of the pericruciate cortex, small degenerating terminals were occasionally observed making contact onto intermediate and distal dendrites. Degenerating rubral terminals were observed synapsing on somata, somatic and dendritic spines, proximal dendrites and most commonly on intermediate and distal dendrites following lesioning of the red nucleus. The degenerating axosomatic rubro‐LRN terminals belonged to the large, round‐vesicle terminal population, while those degenerating terminals contacting intermediate and distal dendrites belonged to the small, round‐vesicle population. Small, degenerating terminals were occasionally seen following lesions of the fastigial nucleus, and they made synaptic contact mainly onto intermediate and distal dendrites and dendritic spines.The present ultrastructural observations taken together with the convergence pattern of LRN afferents and the available electrophysiological data on inputs to the LRN suggest an extensive integration of converging impulses from two or more afferent sources to the rostral LRN neurons. The results of this study therefore support the view that the rostral LRN functions as a comparator of command signals from the motor cortex and red nucleus and feedback signals from the spinal cord and cerebellum during ongoing movement.
A diffuse, invaginating cone bipolar cell in primate retina
Authors: Mariani Andrew P. 
Published: January 2005

AbstractA bipolar cell type forming invaginating contacts with many cones was found by light and electron microscopy of Golgi preparations of the rhesus monkey retina. This diffuse, invaginating cone bipolar cell resembles, superficially, rod (“mop”) bipolars, and so may correspond to Polyak's “brush” bipolar. However, it differs from rod bipolars in that its dendrites are finer and they end in a single stratum containing cone pedicles in the outer plexiform layer (OPL). In the inner plexiform layer (IPL) its axon terminal is located sclerad (S4) to those of rod bipolars (S5), is thinner, and also more branched, and wider in span than rod bipolar axon terminals. Resectioning of Golgi‐impregnated diffuse, invaginating cone bipolars to study their connections in the OPL shows that their dendrites invaginate as many as seven cone pedicles, and terminate as central elements at the ribbon synaptic complex. Thus, the primate retina has multiple (diffuse) and single (midget) cone‐contacting bipolar cell pathways in both invaginating as well as flat varieties.
Afferents to the midbrain auditory center in the bullfrog, Rana catesbeiana
Authors: Wilczynski Walter 
Published: January 2005

AbstractHorseradish peroxidase (HRP) histochemistry was used to visualize cells afferent to the bullfrog torus semicircularis. These afferent cells are located in several sensory and nonsensory nuclei. The sensory structures which project to the torus are mainly auditory nuclei, with the major input coming from the ipsilateral superior olive. A very small contralateral projection is also present. In addition, afferents arise from the contralateral, and to a lesser extent ipsilateral, dorsal acoustic nucleus and nucleus caudalis, both primary eighth nerve nuclei. A vestibular input is also apparent in that HRP‐positive cells were seen in the magnocellular vestibular nucleus and among elongated bipolar cells at the ventral border of the eighth nerve nuclei. In addition, the torus receives somatosensory input from the contralateral perisolitary band. Afferents from spinal cord cells proved difficult to visualize. Nonsensory areas throughout the brain innervate the torus as well. In the medulla, HRP‐positive cells were present bilaterally in both medial and lateral reticular areas. The tegmentum contributes a major input from the superficial isthmal reticular nucleus and a minor input from the tegmental fields. Commissural toral projections are also present. Descending forebrain input arises from the pretectal gray bilaterally, the ventral half of the ipsilateral lateral pretectal nucleus, and, possibly, from the ipsilateral posterior thalamic nucleus. HRP‐positive cells were also occasionally seen in the posterior tuberculum, ventral hypothalamus, and caudal suprachiasmatic preoptic area. Finally, a telencephalic projection from the ipsilateral anterior entopeduncular nucleus is present.
Postnatal histogenetic death of rat forelimb motoneurons
Authors: Rootman D. S. , Tatton W. G. , Hay M. 
Published: January 2005

AbstractPrevious workers have reported a five fold decrease in motoneuron numbers occurring from birth to adulthood in the rat. It has also been reported that forelimb muscles receive connections from motoneurons in both ventral horns prior to day 14 of life in the rat and that the contralateral cells subsequently degenerate completely by day 21. In the present study, postnatal changes in motoneuron number and distribution within the ventral horn were studied in the rat using the technique of retrograde horseradish peroxidase (HRP) transport following intramuscular infusion of HRP into biceps brachii (BB). Peripheral nerves other than those to BB were sectioned and ligated to control for HRP diffusion. The spatial organization of BB motoneurons was compared in animals 9‐14 days old and adult animals using computer 3‐D reconstruction. This allowed observations of the BB motoneurons from a variety of perspectives in relationship to a number of spinal cord landmarks and avoided the necessity for transverse and horizontal sectioning of the cords in alternate animals. A decrease of 50‐75% in the number of HRP filled motoneurons number was found from birth to adulthood (adults 98‐150, neonates 172‐243). The spatial arrangement of the BB motoneurons with regard to the root entry zones and other landmarks such as the dorsolateral convexity of the ventral horn, remains constant from birth to adulthood. No evidence was found to support the existence of inappropriate connections from motoneurons in either the ipsi or contralateral ventral horns of neonate rats. It is suggested that the comparatively small decrease in motoneurons postnatally could be a continuation of the histogenetic processes of cell death begun in utero and is related to the postnatal development of the central and peripheral connections of motoneurons.
Olivocerebellar projections to the pyramis and copula pyramidis in the rat: Differential projections to parasagittal zones
Authors: Eisenman Leonard M. 
Published: January 2005

AbstractThe organization of the olivocerebellar projection to the pyramis and copula pyramidis in the rat has been studied with the use of microinjections of horseradish peroxidase (HRP). These injections were made in different mediolateral positions along the width of this lobule. The objective was to determine the subnuclear origin of parasagittal zones of olivary innervation. The results indicate that six zones of varying width can be distinguished, each of which receives a different olivary projection. Injections in the pyramis in succedingly more lateral positions resulted in retrograde labeling of the lateral part of the caudal medial accessory olive (MAO), nucleus ß of the MAO, and a slightly more rostral part of the lateral MAO. Injections in the copula pyramidis result in retrograde labeling of the lateral part of the dorsal accessory olive (DAO), the intermediate part of the MAO, and the caudal tip of the principal olive. In very few of the experiments was there labeling of more than one subnuclear locus within the inferior olivary complex. These results suggest that parasagittal zones within the pyramis and copula pyramidis of the rat cerebellum receive highly ordered and differential projections from the inferior olivary complex.
Fine structure of the superficial layers of the viper optic tectum. A golgi and electron‐microscopic study
Authors: Repérant J. , Peyrichoux J. , Rio J. P. 
Published: January 2005

AbstractThe superficial layers of the viper optic tectum, which receive fibers from the retina, were studied using both light and electron microscopes. The optic fibers layer, or stratum opticum, is composed of 200 to 250 tight fascicles containing thin fibers, nearly all of which are myelinated. In the main optic terminal layers, the stratum griseum et fibrosum superficiale, the greatest part of the cellular population is composed of small vertically oriented neurons and horizontal nerve cells, many of which are probably local circuit neurons.The neuropil of the stratum griseum et fibrosum superficiale is made up of small nerve elements, including three types of profiles containing synaptic vesicles: (1) boutons with pleiomorphic synaptic vesicles (P), representing over 47% of the total population of profiles containing synaptic vesicles and comprising three subgroups (P1, P2, and P3); (2) boutons with spheroidal synaptic vesicles (S), forming more than 29% of the total population of profiles containing synaptic vesicles and comprising two categories, S1 and S2 (S2, the more numerous, represents the optic boutons, which make up 22% of the total population of profiles containing synaptic vesicles); and (3) dendrites with pleiomorphic vesicles, accounting for approximately 23% of the total population of profiles containing synaptic vesicles. A study of synaptic patterns revealed a large number of serial synapses and a lesser number of triplets or triadic synapses. The presynaptic components are boutons containing spheroidal (S1, S2) or pleiomorphic (P1, P2, P3) synaptic vesicles. The intermediate profile was always a dendrite with synaptic vesicles which frequently belonged to the small neurons of the stratum griseum et fibrosum superficiale. Comparison of the present results with other recent data shows that the synaptic circuitry in the optic tectum of Vipera aspis closely resembles the pattern observed in the optic tectum of other vertebrates, ranging from fish to mammals. However, quantitative differences exist, especially with regard to the proportion of dendrites containing synaptic vesicles. Their number seems to be higher in sauropsidians than in mammals, particularly in primates.
Conduction velocity groups in the optic nerve of the north american opossum (Didelphis virginiana): Retinal origins and central projections
Authors: Rowe Michael H. , Wilson Paul D. , Rapaport David H. 
Published: January 2005

AbstractThe axonal conduction velocity groups in the optic nerve of the North American opossum were analyzed electrophysiologically and related to soma size groups of ganglion cells in terms of their retinal origin and laterality of projection. On the basis of analysis of field potentials and single unit responses recorded at the optic disc, three velocity groups were identified (d1, d2, and d3) and estimated to have average conduction velocities of 12, 8, and 5 meters/second. From recordings of the field potential around the perimeter of the optic disc, it was found that the d1 group was equally represented at all points around the disc, whereas the d2 group was largest in amplitude in superior temporal regions. Electrical stimulation of the optic tracts indicated that axons in the d1 group project either ipsilaterally or contralaterally, whereas the d2 group projects predominantly ipsilaterally, and the d3 group projects predominantly contralaterally.In order to relate these physiological data directly to soma size groups, horseradish peroxidase (HRP) was injected into one optic tract, and subsequently the retinae were processed for peroxidase reaction product in the ganglion cells. Labeled cells were seen in contralateral nasal, contralateral temporal, and ipsilateral temporal retina. Cells in all size classes were labeled in contralateral nasal retina. In contralateral temporal retina, labeled cells were either 10–17 μm diameter (small and medium) or 23–27 μm diameter (large), whereas in ipsilateral temporal retina, most labeled cells (94%) were 15–30 μm diameter (medium and large). The correspondence between these conduction velocity groups and the soma size groups described in the preceding paper (Rapaport et al., '81) is discussed.
On the structural and phyletic origin of the aminergic nerves of the hypophysis of frog tadpoles (Rana temporaria) with special reference to pars distalis
Authors: Aronsson Stig , Enemar Anders 
Published: January 2005

AbstractWith the aid of lesion experiments and the Falck‐Hillarp fluorescence technique, it is shown that the aminergic nerves of the hypophysis, including pars distalis, originate in the caudal hypothalamus and reach the gland via a fibre tract in the floor of tuber cinereum. However, some contribution to the eminentia cmediana from the preoptic area could not be excluded.A vasomotor function of the pars distalis nerves is unlikely.Based on a comparative survey the hypothesis is put forward, that the pars distalis nerves, which disappear during the metamorphic climax, are remnants of an aminergic innervation existing together with a hypophyseal portal system as a functional link between brain and pituitary in the fish‐like ancestor of amphibians. Aspects are given on the problem of why a direct pars distalis innervation has neither been retained nor evolved during evolution of tetrapods.
The effects of refeeding after varying periods of neonatal undernutrition on the morphology of Purkinje cells in the cerebellum of the rat
Authors: McConnell P. , Berry M. 
Published: January 2005

AbstractUndernutrition of the rat for the first 30 days of postnatal life is known to permanently alter Purkinje cell (PC) dendritic morphology. The effects of earlier nutritional rehabilitation have not previously been determined.Neonatal rat pups were undernourished by limiting their access to the lactating dam. After 10, 15, or 20 days of food restriction, animals were either killed for histological comparison with normally fed controls, or provided with ad libitum food until 80 dpp, and then killed.Network analysis of Golgi Cox impregnated PCs from the undernourished animals revealed alterations in dendritic length, segment frequency, and branching pattern, which first became apparent at 15 dpp, accompanied by a reduction in the number of granule cells (GCs) per PC. If undernourished animals were refed from 10 or 15 days, however, the total lengths and segment frequencies of their PC trees were indistinguishable from those of controls at 80 dpp, although the 15‐day group showed persistent topological alterations. The GC:PC ratios of these refed groups were also found to be similar to those of the controls. In animals refed after 20 days of undernutrition, network size remained reduced, as did the GC:PC ratio.The different degrees of recovery of PC dendritic field parameters recorded in the refed animals could be related either to enhanced GC replication afforded by refeeding, or to the existence of intrinsic mechanisms which limit the growth capacity of the PC dendrites.
Some observation on the catecholaminergic innervation of the intermediate zone of the thoracolumbar spinal cord of the cat
Authors: McLachlan Elspeth M. , Oldfield B. J. 
Published: January 2005

AbstractThe anatomical arrangement of catecholaminergic nerve terminals in the intermediate zone of the thoracolumbar spinal cord was examined with the fluorescence microscope in serial sections of spinal cord from adult cats perfused with a formaldehyde‐glutaraldehyde mixture. Specific fluorescence in this material was assumed to represent noradrenaline. The distribution of fluorescent varicose nerve terminals was compared with that of neuron cell bodies in the same sections after Nissl counterstaining, and with the known topographic distribution of sympathetic preganglionic neurons. Dense accumulations of noradrenergic fibers were found in the intermediate zone in all segments between the caudal part of C8 and the rostral part of L4. These were not only associated with preganglionic neurons in the intermediolateral columns (ILN), but below T5 also extended in bands (1–3 per mm of spinal cord) toward, and in some segments across, the midline. Noradrenergic terminals were associated with cell bodies in most parts of the ILN from T1 to T8 and in L2–3. Between T9 and L2, the innervation of the ILN was patchy, and the majority of the noradrenergic fibers projected to regions medial to the ILN. These corresponded to sites at which preganglionic neurons and also possible interneurons of the intermediomedial nucleus occur. Although preganglionic neurons and clusters of noradrenergic terminals are located in similar regions across the intermediate zone, their densities and patterns of distribution differ. This observation applies to comparisons both between anatomical subnuclei and between segments in a characteristic way along the length of the thoracolumbar cord.