bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monoamine‐accumulating ganglion cell type of the cat's retina
Authors: Dacey Dennis M. 
Published: January 2005

AbstractA monoamine‐accumulating ganglion cell type has been identified in an in vitro preparation of the cat's retina by a catecholamine‐like fluorescence that appears following intravitreal injections of dopamine and the indoleaminergic transmitter analog, 5,7‐dihydroxytryptamine (5,7‐DHT). A subpopulation of large, weakly fluorescing neurons were identified as composing a single, morphologically distinct ganglion cell type by intracellular injections of horseradish peroxidase (HRP). In a sample of 374 HRP‐filled cells soma diameter ranged from 13–21 μm (mean ± SD = 16.6 ± 1.3). Dendritic field size increased with increasing retinal eccentricity from 150–200 μm diameter at 0.5 mm from the area centralis to 600–800 μm diameter in the far retinal periphery. Dendrites are thin (∼1 μm diameter), show a characteristic branching pattern, and are narrowly stratified at the outer border of the inner plexiform layer. The monoamine‐accumulating ganglion cell and the outer (OFF‐center) alpha cell occupy distinct strata within sublamina a of the inner plexiform layer separated by a gap of about 5 μm.The total number of monoamine‐accumulating (MA) ganglion cells was estimated at 5,400, about 3.5% of the total ganglion cell population. Spatial density of the MA ganglion cells, calculated from cell counts made in vitro, ranges from 60 cells/mm2 near the area centralis to 5 cells/mm2 in the far retinal periphery. A coverage factor (density x dendritic field area) of 2.2 was maintained from central to peripheral retina. The nature of the dendritic overlap was observed directly by making HRP injections into several neighboring ganglion cells. Five to seven neighboring dendritic trees extensively overlapped a given cell's dendritic field. However the dendritic processes did not intersect randomly but tended to interdigitate such that a uniform interdendritic spacing and density of dendritic processes was constructed locally within the dendritic plexus. Rotation of individual dendritic trees from their normal orientation produced a dramatic 4‐5‐fold increase in the number of dendritic intersections, suggesting that an active, local mechanism operates in the precise placement of individual dendrites within the plexus.The monoamine‐accumulating ganglion cell appears morphologically equivalent to the delta ganglion cell (Boycott and Wässle; J. Physiol. (Lond.) 240: 397–419, '74; Kolb et al.; Vision Res. 21: 1081–1114, '81) and to the recently recognized indoleamine‐accumulating ganglion cell (Wässle et al: J. Neurosci. 7: 1574–1585, '87). Comparisons with previous studies indicate that they may be physiologically equivalent to the OFF‐center, sluggish sustained cells (also known as tonic W cells and Q cells) and probably project to the superior colliculus and/or the C‐lamina of the dorsal lateral geniculate nucleus.
Early neurogenesis of the mouse olfactory nerve: Golgi and electron microscopic studies
Authors: Marin‐Padilla Miguel , Amieva B. Manuel R. 
Published: January 2005

AbstractThe early neurogenesis of the mouse olfactory nerve, from its exit at the nasal epithelium to its entrance into the embryonic telencephalon, has been investigated by using the rapid Golgi method and electron microscopy. Previously unrecognized anatomical and possible functional interrelationships between developing olfactory nerve axons and their sheath cells have been observed: (1) at their exit from sensory epithelium (nasal compartment), (2) at their contact with the CNS surface (intracranial compartment), and 3) at their entrance into the embryonic telencephalon (central nervous tissue compartment). Based on these observations the anatomy of the mouse olfactory nerve is herein redefined. Exiting olfactory nerve axons and sheath cells from the same regions of the nasal epithelium establish an early association which is maintained up to their terminal glomerular neuropile. No disruptions have been found in either the olfactory nerve axons or in the continuity of their sheath cells from exit at the nasal epithelium to entrance into the developing olfactory bulb. Corresponding olfactory nerve axons with their sheath cells enter together and become incorporated into the developing olfactory bulb as units. Consequently, the cellular envelope of the olfactory glomerulus must be composed of olfactory sheath cells rather than of glial (astroglial) cells from the CNS. With this simple anatomical arrangement, a topographic map of the sensory epithelium could be established progressively in the developing olfactory bulb. Eventually, “regenerating” olfactory nerve axons from different nasal regions could be guided by their specific sheath cell conduits toward their target glomeruli; hence, the olfactory message may be maintained undisturbed throughout the life span of the animal. In addition, olfactory nerve axons establish synaptic‐like contacts with their corresponding sheath cells prior to or during the perforation of the CNS surface. Reciprocal recognition between corresponding axons and their sheath cells at this crucial stage in their neurogenesis may play a significant role in the establishment of their terminal glomerulus. This new concept of the anatomy of the mammalian olfactory nerve should provide insights helpful in clarifying some of the still‐unresolved questions regarding the structural and functional organizations of this primitive system.
Neuronal and synaptic measurements in the visual cortex of adult rats after undernutrition during normal or artificial rearing
Authors: Bedi K. S. , Massey R. F. , Smart J. L. 
Published: January 2005

AbstractIt is possible that the reported effects of early life undernutrition on brain morphology may be due to alterations in mother‐infant interactions and not directly to undernutrition. We have investigated this possibility by comparing artificially reared with mother‐reared rats. Four groups of black‐and‐white hooded male rats were reared. These consisted of mother reared control (MRC), mother reared undernourished (MRU), artificially reared control (ARC) and artificially reared undernourished (ARU). Artificially reared rats were raised in isolation away from their mothers from 5 to 21 days of postnatal age. They were fitted with a gastric cannula through which 'milk' was infused automatically. The period of undernutrition lasted from 5 to 25 postnatal days, following which the animals were fed ad libitum until 312 days of age. Rats from each group were then killed by perfusion with buffered 2.5% glutaraldehyde. Pieces of visual cortex from each rat were postfixed in osmium tetroxide and embedded in resin. Stereological procedures at the light and electron microscopical levels were used to estimate the synapse‐to‐neuron ratios in cortical layers II to IV.Both MRC and ARC rats had about 7000 synapses per neuron. However, this ratio was about 8300 in MRU rats whilst it was only about 5000 in ARU animals. The rearing x nutrition interaction was statistically significant at the 0.1% level. These changes in the synapse‐to‐neuron ratio were mainly due to alterations in the numerical densities of the synapses rather than that of neurons.These results demonstrate that environmental isolation, as a result of artificial rearing procedures, and concurrent undernutrition during the first three weeks of postnatal life, interact with one another to produce marked morphological changes in the adult rat brain. However, environmental isolation was not, by itself, sufficient to cause permanent changes in interneuronal connectivity.
Ultrastructural relationships of serotonin axon terminals in the cerebral cortex of the adult rat
Authors: Séguéla Philippe , Watkins Kenneth C. , Descarries Laurent 
Published: January 2005

AbstractPAP immunocytochemistry with an antiserum against serotonin (5‐HT)‐glutaraldehyde‐protein conjugate (kindly donated by M. Geffard) was used to analyze the ultrastructural relationships of 5‐HT axon terminals (varicosities) in the frontal (Fr1‐Fr2), parietal (Par1), and occipital (Oc1M‐Oc2) cortex of adult rats. One hundred‐forty‐five immunostained varicosities from Fr1‐Fr2 (54 from layers I‐II; 91 from layer VI) and 97 each from the upper layers (I‐II) of Par1 and OcM1‐Oc2 were examined in groups of serial thin sections (mean number of sections in series: 3.2 to 7.3). These terminals were of comparable shape and size in the 4 cortical sectors examined, and averaged 0.66 ± 0.2 μm in mean diameter. The proportion of varicosities engaged in synaptic contact was evaluated by linear transformation of the relationship between the frequency of observed synaptic junctions and the number of thin sections available for examination. Reliability of the sampling was evidenced by a high coefficient of correlation (r> 0.95) in each cortical sector. The synaptic incidence extrapolated for whole varicosities ranged from 28% (layer VI of Fr1‐Fr2) to 46% (Par1), without statistically significant differences between the 4 sectors examined. The interregional mean could thus be evaluated at 38%. The synaptic 5‐HT terminals always made asymmetrical junctions, which were exclusively found on dendritic spines and shafts, and appeared more frequent on spines than shafts in the deep frontal and the upper occipital cortex. In all 4 sectors, dendritic shafts and spines and other axonal varicosities were frequently encountered in the immediate microenvironment of the immunostained varicosities. It is concluded that the cortical 5‐HT innervation is predominantly nonjunctional throughout the neocortex of the adult rat, which reinforces earlier views of a highly divergent afferent system with particular functional properties and perhaps capable of widespread, global and/or sustained influences in this part of the brain.
Cholinergic amacrine cells in the developing cat retina
Authors: Dann J. F. 
Published: January 2005

AbstractAntiserum directed against the ACh‐synthesizing enzyme choline acetyltransferase (ChAT) was used to determine the development of cholinergic amacrine cell distributions in wholemounted kitten retinae. From birth (P0) two populations of cholinergic amacrine cells were immunolabelled; one population was located in the inner nuclear layer (INL) and the other was displaced to the ganglion cell layer (GCL). Dendrites from cholinergic amacrines in the INL stratified in the outer third of the inner plexiform layer (IPL), whilst those from displaced amacrines in the GCL stratified in the centre of the IPL. There was a centroperipheral gradient of development in both populations, and the total number of cholinergic amacrines in the GCL always exceeded that of the INL.The most dramatic increase in the number of amacrines expressing ChAT was between P0 and P5 when the numbers doubled. During the same period there was an increase in the soma size of both populations in the peripheral retina. In the GCL, cholinergic amacrines did not attain adult size until P21 whereas those of the INL reached adult proportions by P5. Overall, between P0 and P21 there was a fivefold increase in the number of immunoreactive cholinergic amacrines in the GCL and a 3.5‐fold increase in those of the INL. In general, the distribution, soma size, percentage per layer, and total number of cholinergic amacrines in both populations resembled those of the adult by P21.
Crossed and uncrossed projections to cat sacrocaudal spinal cord: I. Axons from cutaneous receptors
Authors: Ritz Louis A. , Brown Paul B. , Bailey Steven M. 
Published: January 2005

AbstractIntra‐axonal recording and horseradish peroxidase staining techniques were used to map terminal fields of primary afferent fibers from cutaneous receptors within the cat sacrocaudal spinal cord. It was hypothesized that projection patterns of cutaneous afferent fibers mirror the known somatotopic organization of sacrocaudal dorsal horn cells.Forty‐three primary afferent fibers, innervating either slowly adapting type I receptors, hair follicles, or slowly adapting type II receptors, all on the tail, were recovered. All collaterals (N = 372) branched from parent axons in the dorsal columns. Most collaterals coursed rostromedially to the ipsilateral gray matter, penetrated the medial dorsal horn, and arborized within laminae III, IV, and to a lesser extent, V.Ipsilateral projections to dorsal horn were as follows: axons with dorsal or dorsolateral receptive fields (RFs; n = 20) to the lateral portion, axons with lateral RFs (n = 4) to the central portion, and axons with ventral or ventro‐lateral RFs (n = 19) to the medial portion. Most axons (16 of 20) with dorsal or dorsolateral RFs also had contralateral projections to lateral dorsal horn and most axons (15 of 19) with ventral or ventrolateral RFs also had contralateral projections to medial dorsal horn. No axons with lateral RFs had crossed projections.These data represent the first complete mapping of the somatotopic organization of primary afferent fiber projection patterns to a spinal cord level. The findings demonstrate that ipsilateral projection patterns of sacrocaudal primary afferent fibers are in register with the somatotopic organization of the dorsal horn. Our earlier suggestion that crossed projections of primary afferent fibers give rise to crossed components of dorsal horn RFs spanning the midline is supported by these results.
Morphology and somatotopic organization of the central terminals of hindlimb hair follicle afferents in the rat lumbar spinal cord
Authors: Shortland Peter , Woolf Clifford J. , Fitzgerald Maria 
Published: January 2005

AbstractThe morphology of the central collateral arborizations of 24 A‐beta hair follicle afferents (HFAs) innervating different regions of the skin of the hindlimb were studied by the intra‐axonal injection of horseradish peroxidase (HRP) in adult rats. A total of 236 collaterals were recovered. These fell into three classes—complex, simple, and blind‐ending—based on numbers of boutons and terminal branch patterns. The morphology of the HFA central arbors innervating the lateral and medial leg and dorsum of the foot was flameshaped. Afferents with receptive fields on the glabrous‐hairy skin border consistently had extra terminal branches running ventromedially into laminae IV/V. Differences in the width of terminal arbors were found. HFA terminals innervating the lateral leg formed narrower sheets than those innervating the dorsum of the foot and toes.The somatotopic organization of the collaterals and terminal arborizations of individual afferents were analyzed both by considering all the collaterals along an axon's rostrocaudal extent and by only examining arbors with boutons (the complex and simple arbors). Thirty‐seven percent of blind‐ending and 18% of simple collaterals were found to overlap in the rostrocaudal direction with the complex arborizations of afferents whose receptive fields were in a different cutaneous nerve territory. There was no overlap between complex arborizations of afferents from different nerve territories. However, the complex arbors of afferents with receptive fields within a particular nerve territory showed considerable terminal overlap even if they had nonadjacent peripheral receptive fields. The topographical organization of the central terminals of HFAs, forms a coarse somatotopic map of overlapping terminals whereby a particular region of dorsal horn has a maximal, but not exclusive, input from a particular area of skin.
Early postnatal cellular proliferation and survival in the olfactory bulb and rostral migratory stream of normal and unilaterally odor‐deprived rats
Authors: Frazier‐Cierpial Lauren , Brunjes Peter C. 
Published: January 2005

AbstractUnilateral naris occlusion in rats on postnatal Day 1 results in dramatic decreases in the size of specific olfactory bulb cell populations when pups are examined 30 days later (Frazier and Brunjes: J. Comp. Neurol. 269:355–370, '88). The observed reductions must result from alterations in cell proliferation and/or survival, alternatives examined in the present study.During early postnatal development, most cells destined for the bulb are produced in regions caudal to the structure and migrate to the bulb in the massive rostral migratory stream. The dynamics of the stream were examined in both normal rats and pups with a single naris closed on Day 1. 3H‐thymidine injections were made on postnatal Days 2, 5, 10, 20, and 30. Groups of pups were killed 2 hours later to assess patterns of proliferation and 24 hours later to gauge initial stages of migration. A gradient of labeled cells was observed in the stream, with higher levels occurring at more caudal locations. The supply of cells to the bulb peaked on Day 5 and was still substantial as late as Day 30. The deprivation procedure did not affect patterns of cell labeling at any stage tested, indicating the procedure does not affect early cellular proliferation.A third group of pups was examined 30 days after thymidine injection to assess both time of cell origin and survival rates. Dark granule cells and glia in the granule cell layer were produced at a consistent rate until Day 20 with cells added during the period evenly spread throughout the layer. Light granule and periglomerular cell production decreased dramatically after P5. Thirty days after injections on P2, fewer labeled dark granule cells and their associated glia were found in deprived bulbs, indicating that enhanced cell death plays a major role in the deprivation‐induced decrease in cell number.
Morphometric modifications associated with early sensory experience in the rat olfactory bulb: I. Volumetric study of the bulbar layers
Authors: Royet J. P. , Jourdan F. , Ploye H. 
Published: January 2005

AbstractCurrent models of sensory coding in the olfactory bulb are based on the notion of topographical specificity in the processing of stimuli. Part of this hypothesis comes from studies of patterns of radiolabelled 2‐deoxyglucose uptake, and local morphometric variations of the mitral cell size observed following prolonged exposure to an odor. The present study explored the possibility that exposing young rats to a long‐term stimulation with an odor would induce spatially distributed volumetric variations of the bulbar layers. Three groups of 5 rats have been studied: (1) stimulated with ethyl acetoacetate from birth to 1 month of age, (2) unilaterally deprived following early cauterization of one nostril, and (3) normal animals of same age. Fourteen frontal histological sections uniformly distributed along the rostrocaudal axis of the olfactory bulb were used for this study. Areas of the bulbar layers were measured with the aid of an image analyser and the volume of the corresponding layers deduced by computation. Following complete sensory deprivation, the volume of all bulbar layers, except the periventricular core, was homogeneously reduced along the rostrocaudal axis of the olfactory bulb. Following long‐term stimulation with ethyl acetoacetate, volume reduction was significantly higher in anterior and middle regions than in the posterior part of the olfactory bulb. It is assumed that neuronal pathways activated by ethyl acetoacetate stimulation are mainly located in the posterior part of the olfactory bulb. Functional interpretations of these results are discussed with respect to the spatial dimension in olfactory coding.
Anatomical evidence of the projection of pontine omnipause neurons to midbrain regions controlling vertical eye movements
Authors: Ohgaki Tohru , Markham Charles H. , Schneider Jay S. , Curthoys Ian S. 
Published: January 2005

AbstractBoth anatomical and physiological studies have shown that pause neurons (PNs) in the medial pontine reticular formation project to two groups of burst neurons (BNs) involved in the genesis of horizontal saccadic eye movements: The excitatory burst neurons (EBNs), which lie rostral to the abducens nucleus, and the inhibitory burst neurons (IBNs), which lie caudal to the abducens. This study is concerned with the projection from PNs to a group of vertical BNs in the nucleus of the H field of Forel (H FF) in the caudomedial subthalamus. Three anatomical methods were used to demonstrate this connection.First, intra‐axonal horseradish peroxidase (HRP) injection into physiologically identified PN axons demonstrated axonal branching and axonal terminations in and around the H FF. Second, micro‐injection of the tracer Phaseolus vulgaris leucoagglutinin (PHA‐L) into the pontine PN region labelled terminal axons and boutons in the nucleus of the H FF. Third, extracellular pressure injection of HRP into H FF yielded retrogradely labelled pontine PN neurons. These anatomical results confirmed the termination of PNs in areas controlling rapid vertical eye movements as physiologically demonstrated by Nakao et al.: Exp. Brain Res. 70:632–636, (88). This work points to the major role of pontine PNs in the synchronization of BN activity in rapid eye movements in all directions.
Organization of the projections from the trigeminal brainstem complex to the superior colliculus in the rat and hamster: Anterograde tracing with Phaseolus vulgaris leucoagglutinin and intra‐axonal injection
Authors: Rhoades Robert W. , Fish Stephen E. , Chiaia Nicolas L. , Bennett‐Clarke Carol , Mooney Richard D. 
Published: January 2005

AbstractAnterograde tracing with Phaseolus vulgaris leucoagglutinin (PHA‐L) and intra‐axonal recording and injection techniques were employed to describe the projection from the trigeminal (V) brainstem complex to the deep laminae of the superior colliculus (SC) in the hamster and the rat. The organization of these projections was the same in the two species. Deposits of PHA‐L into V nucleus principalis (PrV) produced labelled axons and boutonlike swellings in the lower stratum griseum intermediale (SGI) and upper stratum album intermedium (SAI) in the SC bilaterally. Plots of boutonlike swellings indicated that the terminals of this projection were arrayed in clusters. Nucleus principalis also projected to the stratum griseum profundum (SGP) and stratum album profundum (SAP). This deeper projection did not terminate in clusters and it was most prominent in the lateral SC. The ipsilateral PrV‐SC projection appeared to arise mainly from axons that recrossed the midline at the level of the SC commissure. Reconstruction of individual PHA‐L labelled fibers demonstrated that single axons gave rise to terminals on both sides of the midline. Deposits of PHA‐L into V subnucleus interpolaris (SpI) yielded results that were identical to those obtained with PrV injections with one exception: none of these deposits produced any labelled terminals in the ipsilateral SC. Deposits of PHA‐L into V subnucleus caudalis (SpC) produced only sparse labelling in SC. Most labelled swellings were located in the SGP and SAP and they were visible only in the SC contralateral to the PHA‐L injection site. Single axons arising from cells in SpI were recorded and injected with horseradish peroxidase (HRP) in the hamster's SC. These fibers all responded to stimulation of multiple mystacial vibrissae and gave rise to 2–5 clusters of bouton‐like swellings in the lower SGI and upper SAI.