bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glycogen phosphorylase activity in the olfactory bulb of the young rat
Authors: Coopersmith Robert , Leon Michael 
Published: January 2005

AbstractThe activity of glycogen phosphorylase, the enzyme that controls glycogen breakdown, was histochemically mapped in the olfactory bulbs of 19‐day‐old rats. The effect of early odor experience on subsequent olfactory bulb phosphorylase activity was also examined. The highest level of phosphorylase staining in the bulb (and seemingly the highest in the brain) was in the glomerular layer, followed by the external plexiform, internal plexiform, granule cell, and olfactory nerve layers. Virtually no activity was visible in the large output neurons of the bulb, mitral, and tufted cells. Early peppermint odor experience, previously shown to increase metabolic activity in specific glomerular foci as measured by 2‐deoxyglucose uptake, had no apparent effect on glomerular‐layer phosphorylase activity. In some odor‐familiar animals, however, patches of activity were seen in the internal plexiform layer in the area of the bulb where foci of high deoxyglucose uptake are seen in response to peppermint. The patches were directly in line with modified glomerular clusters often seen to underlie foci of enhanced deoxyglucose uptake.The existence of particularly heavy activity in the peripheral third of the glomerular layer, where glycogen‐containing modified Schwann cells have been localized, raises the possibility that the glomerular‐layer activity is at least partially glial in origin. Finally, because of its rich noradrenaline and serotonin innervation and high density of insulin receptors, the olfactory bulb is proposed as a model system to study the interaction of glycogen/glucose metabolism with neural activity in a relatively well‐defined neuronal circuit.
Motoneuron number in the lumbar lateral motor column of larval and adult bullfrogs
Authors: Farel Paul B. 
Published: January 2005

AbstractMotoneuron number in the lumbar lateral motor column of the bullfrog, Rana catesbeiana, was investigated through the course of premetamorphic development and in postmetamorphic frogs. Motoneurons were distinguished on the basis of histological characteristics into two classes, type L (less differentiated) and type M (more differentiated). The number of type L motoneurons on each side showed a precipitous decline between stages V and VI (6,300 to 2,500) and a slower rate of loss until stage XI (to 550). Type M motoneurons increased in number between stages V and VII (560 to 2,775) and declined precipitously between stages VII and VIII to a value similar to that of juvenile frogs (1,100). These changes in motoneuron number do not correspond to the formation of myotubes or to the appearance of contractile properties in hindlimb muscles. The development of myotubes in the hind‐limb occurs only after total motoneuron number has declined by 35%. Similarly, hindlimb muscle contraction develops after the early decline in type L motoneuron number and is restricted to proximal thigh at the peak of type M motoneuron number.In postmetamorphic frogs, a weak (r = 0.44) but statistically significant correlation was found between type M motoneuron number and body length. In the largest frogs (greater than 15 cm body length), 1262 ± 157 (mean ± s.d.) motoneurons were present, whereas the smallest frogs (less than 5 cm body length) had 1099 ± 98 motoneurons. These results are not consistent with previous findings that the variance of motoneuron number among small frogs is greater than that among larger frogs. The present results are thus inconsistent with explanations of size‐related differences in motoneuron number that are based on selection of small frogs with greater number of motoneurons for survival. The increase in motoneuron number may be due to a slow addition of newly born motoneurons to the LMC or to the differentiation of existing motoneurons. The latter possibility is supported by the finding that the number of presumptive type L profiles is less in larger frogs.
Stereological analysis of synaptogenesis in the molecular layer of piriform cortex in the prenatal rat
Authors: Newman‐gage Helen , Westrum Lesnick E. , Bertram John F. 
Published: January 2005

AbstractThe development of synapses in the molecular layer of the rat piriform cortex was studied at embryonic days 15, 17, 19, and 21. The present study has sought to extend past studies of synaptogenesis by identifying not only changes in numbers of synapses, but also changes in numbers of potential precursors of synapses. A stereological method (Cruz‐Orive, ′80) was used to make volumetric estimations of the numbers of synapses, axonal puncta, vesicle‐associated puncta, and unapposed postsynaptic specializations. This stereological method was preferred to other morphometric methods because it is not influenced by changes in the size, shape, or orientation of the structures of interest. This was considered important since such changes might be expected during development.Large numbers of unapposed axonal specializations (axonal puncta and vesicle‐associated puncta) were found in all three sublaminae (lateral olfactory tract, Ia, and Ib) at all ages. The numerical density (number per unit volume of neuropil) and relative frequency of these structures changed significantly with time. In all three sublaminae, these changes were associated with changes in the number of synapses, although the numerical density and relative proportions varied between the sublaminae. These results suggested that axonal puncta could accumulate vesicles, thus becoming vesicle‐associated puncta, and that vesicle‐associated puncta could contact dendrites, thus forming synapses. In contrast, the numerical density of lone postsynaptic specializations remained low and no significant changes in their relative proportion in the population were found. This suggested that although lone postsynaptic sites were observed, they did not appear to play a major role in synaptogenesis in this region of the cortex. In addition to documenting developmental differences between the three sublaminae in the molecular layer, the results support a synaptogenic hypothesis in which the axon can form surface specializations that appear to be involved in synaptogenesis, independent of direct dendritic contact.
Distribution of external cuneate nucleus afferents to the cerebellum: II. Topographical distribution and zonal pattern‐an experimental study with radioactive tracers in the cat
Authors: Jasmin L. , Courville J. 
Published: January 2005

AbstractSmall injections of tritiated leucine and the autoradiographic method were used to demonstrate efferents from restricted portions of the external cuneate nucleus (NCE) to the cerebellum. Sites of injection were analyzed by reference to the distribution of primary muscle afferents in NCE. On transverse sections, the silver deposits form longitudinal bands that, in certain regions, are packed together and label the entire surface of the granular layer; in other parts, they are separated by empty longitudinal bands. The longitudinal deposits are not continuous in the rostrocaudal direction. On the basis of the distribution of the longitudinal bands, 14 zones have been described for lobules II‐VI, and 6 zones were recognized in lobules I, VIII, and the paramedian lobule. Afferents from NCE are distributed topographically. Regions of the nucleus receiving axial and neck muscles project mainly to vermal regions of lobules I‐III, and to parts of lobules VIII and IX. Regions receiving afferents from forelimb muscles send their fibers preferentially to the vermian region of lobule V, to paravermian regions of lobules IV‐VI, to parts of lobules VIII and IX, and to the paramedian lobule. These distributions in several respects are in agreement with the somatotopical maps of the cerebellum. However, other features support a “mosaic” arrangement: efferents from a region of NCE are distributed over several distinct sites of the cortex and efferents from different parts of the nucleus also converge to neighboring cortical regions.
Retinal ganglion cells projecting to the accessory optic system in the rat
Authors: Dann Joan F. , Buhl Eberhard H. 
Published: January 2005

AbstractThe present data identify the distribution and morphological features of a homogeneous group of rat retinal ganglion cells. These cells were labelled after injection of either horseradish peroxidase or a fluorescent tracer, Fast Blue, into the medial terminal nucleus (MTN) of the accessory optic system. After retrograde fluorescent labelling, MTN‐projecting retinal ganglion cells were intracellularly injected with Lucifer Yellow to reveal their complete dendritic morphology.There were on average 1,750 MTN‐projecting cells fairly evenly distributed over the entire retinal ganglion cell layer. Their density ranged from 40–49 cells/mm2 in superior retina to 10–19 cells/mm2 towards the peripheral regions of both inferior and superior retina. The area of highest density formed a nasal‐temporal band suggestive of a visual streak.Soma diameters ranged from 8.7 to 14.5 μm centrally and from 9.9 to 17.1 μm peripherally. Maximal dendritic field diameter ranged from 431 to 644 μm and averaged 516 μm with no obvious eccentricity dependence.The majority of MTN‐projecting cells were bistratified. Dendrites stratified predominantly in the inner sublamina of the inner plexiform layer (IPL) with a varying number of branches from the remaining dendrites contained within the outer IPL, both strata presumably corresponding to the electrophysiologically determined on‐off dichotomy.Cells projecting to the MTN were characterised by higher‐order dendritic branching patterns that resulted in a dense dendritic tree with minor dendritic overlap. The slender dendrites had a beaded appearance and displayed spiny protrusions. The dendritic coverage of 5–6, stratification pattern, and overall morphological appearance of rat MTN‐projecting cells renders them suitable candidates for on‐direction‐selective cells shown electrophysiologically to be linked with the MTN of the accessory optic system.
Variation in the mode of receptor cell addition in the electrosensory system of gymnotiform fish
Authors: Zakon Harold H. 
Published: January 2005

AbstractAge‐related changes in ampullary and tuberous receptor organ morphology were studied in six species of gymnotiform weakly electric fish. Cheek skin was silver‐stained, whole‐mounted, and viewed under Nomarski differential interference contrast optics. The ampullary receptor units of all species show an increasing number of receptor organs per afferent fiber with fish size, presumably the result of addition of newly formed receptor organs. Ampullary units composing over a dozen organs were observed in large specimens of a few species. Receptor cells were also added in the tuberous receptor system of all species, but in different ways. As previously reported for Sternopygus, small specimens of Eigenmannia had only a single tuberous receptor organ per afferent. Fish of increasing size retained a population of afferents that innervated only a single receptor organ and, in addition, had a population of afferents that innervated a cluster of receptor organs. The mean number of receptor organs per cluster increased in fish of increasing size. In addition, the mean number of sensory receptor cells per organ increased. New organs presumably derive from older ones, which divide under the stimulus of continued addition of new receptor cells. Apteronotus, Adontosternarchus, and Hypopomus all added more receptor cells to their tuberous organs. In these species, every afferent innervated only a single tuberous organ and there was no indication of division of receptor organs. Gymnorhamphichthys and Gymnotus were intermediate in that they added new receptor cells to each receptor organ, and, in larger fish, these were segregated into discrete patches within a single receptor organ. It is likely that the additon of new receptor cells aids in increasing sensitivity of both ampullary and tuberous receptors as fish grow.
Synaptic structure of the monoamine and peptide nerve terminals in the intermediolateral nucleus of the guinea pig thoracic spinal cord
Authors: Chiba Tanemichi , Masuko Sadahiko 
Published: January 2005

AbstractSynaptic organization of the intermediolateral nucleus of the guinea pig thoracic spinal cord was examined with particular focus on monoamine‐ and peptide‐containing nerve terminals. Axon varicosities having flat synaptic vesicles constituted 17% of all axons in the nucleus and formed exclusively symmetric synapses. Enkephalin‐, substance P‐, somatostatin‐, 5‐hydroxytryptamine‐, and catecholamine‐immunoreactive nerve terminals were densely distributed, while neurotensin‐, vasoactive intestinal polypeptide‐, oxytocin‐, and cholecystokinin‐8‐immunoreactive nerves were sparse in the nucleus. Coexistence of 5‐hydroxytryptamine and enkephalin was demonstrated, and coexistence of somatostatin and enkephalin as well as somatostatin and 5‐hydroxytryptamine in the same axons was also shown by serial semithin sections. Catecholamine axons labelled by 5‐hydroxydopamine formed axodendritic and axosomatic synapses and made direct synaptic contacts on the preganglionic sympathetic neurons identified by retrograde transport of horseradish peroxidase. Direct synaptic contacts from enkephalin‐ and substance P‐immunoreactive axons to preganglionic sympathetic neurons were also revealed. Enkephalin‐, substance P‐, and 5‐hydroxytryptamine‐imunoreactive axons formed axodendritic and axosomatic synapses. Catecholamine axon varicosities constituted 19% of all axon varicosities in the nucleus and 30% of them showed synaptic specializations in a sectional plane. Axon varicosities immunoreactive to enkephalin, 5‐hydroxytryptamine, and substance P constituted approximately 35, 19, and 13% of all axon varicosities, respectively, while those with synaptic contacts made up 27, 30, and 26%, respectively, in a sectional plane. Enkephalin‐, 5‐hydroxytryptamine‐, and noradrenaline‐immunoreactive axons showed mainly symmetric synaptic contacts.
Retinotopic organization in the dorsal lateral geniculate nucleus of the tammar wallaby (Macropus eugenii)
Authors: Wye‐Dvorak J. , Levick W. R. , Mark R. F. 
Published: January 2005

AbstractElectrophysiological recordings were made from 187 single cells in the tammar wallaby (Macropus eugenii) dorsal lateral geniculate nucleus (LGNd). The results show that it is topographically organized such that the superior visual field is represented dorsally, the inferior field is represented ventrally, the nasal visual field is represented ventrally, and the temporal visual field is represented rostrally.The visual field of one eye ranges from −30° nasal to +179° temporal in azimuth and +73° superior to −49° inferior in elevation. Ganglion cells that had receptive field positions between −9° and +179° projected to the contralateral LGNd while the ganglion cells that projected to the ipsilateral LGNd had visual fields from 0 to +30°.The binocular visual field extends 60° in azimuth. This representation in the LGNd is expanded relative to the monocular representation. There is also an increased representation of the horizon in the temporal field corresponding to the visual streak of retinal ganglion cells. The binocular visual field is located where contralateral and ipsilateral laminae are shown to interdigitate by proline autoradiography.There are nine eye‐specific laminae in the LGNd. Four receive afferents from the contralateral eye and five receive afferents from the ipsilateral eye. The lines of isoelevation are perpendicular to the coronal plane of section while the lines of isoazimuth are nearly parallel to the coronal plane. The lines of projection representing one visual direction are inferred to be perpendicular to the tangent of curvature of the laminae as in the LGNd of other mammals.The majority of cells (85%) recorded had on‐ or off‐centre responses. On‐and off‐centre responses were not apparently segregated in the LGNd but segregation may not have been revealed by the single‐unit recording technique.
Organization of anterogradely labeled spinocervical tract terminations in the lateral cervical nucleus of the cat
Authors: Craig A. D. , Sailer S. , Kniffki K.‐D. 
Published: January 2005

AbstractThe anterograde transport of horseradish peroxidase following injections into the cervical, thoracic, or lumbosacral spinal cord was used to examine the organization of spinocervical tract terminations in the lateral cervical nucleus (LCN) of the cat. A somatotopic organization of the labeling originating from different spinal levels was observed in the mediolateral dimension. Cervical labeling generally occurred in the ventromedial portion and lumbosacral labeling in the dorsolateral portion of the LCN. Thoracic labeling occurred both in the middle and the most lateral edge of the nucleus. In all cases, labeling was distributed over most of the rostrocaudal extent of the LCN. In addition, distinct patches of labeling were present in the medialmost portion of the nucleus, regardless of the spinal level injected. These observations corroborate the topographical organization of the LCN described previously on the basis of physiological and retrograde labeling data, and support the identification of the medialmost part of the LCN as a distinct portion of the nucleus.Terminal labeling in the LCN always occurred in multiple, longitudinally distributed fields. The afferent input to each terminal field coursed in separate, loose bundles of fibers that descended from the superficial dorsolateral funiculus. Large injections resulted in more extensive, overlapping terminal fields. These observations indicate that collateral projections result in several discrete representations of a given portion of the skin over the longitudinal extent of the LCN, but that topographical relationships are longitudinally maintained. It is suggested that these multiple terminal fields are the anatomical correlate of the functionally selective convergence of spinocervical tract terminations, that has previously been postulated on physiological grounds to explain the generation of LCN receptive fields with homogenous receptor input within a somatotopic framework.
Counting sectioned cells via mathematical reconstruction
Authors: Rose Robert D. , Rohrlich Daniel 
Published: January 2005

AbstractA new method for determining the number of neurons in sectioned tissue is presented. The method does not involve identification of subcellular structures; rather, it uses estimates of the mean diameters of sections of the neuronal somata (with or without nuclei). All such sections are termed profiles. A mathematical model is developed to reconstruct the cell population from a size histogram of the profiles. Although the model is simple, the calculations are numerous and best done on a computer. A program that performs these calculations is provided. We discuss the idealizations on which the model is based and test the method in various ways: on hand‐ and computer‐generated data in which imaginary spheres of known size were sectioned; on two small samples of real cells for which both cell and profile size histograms were available; and on a sample of potatoes, sliced by hand. In every case the estimate was within 10% of the actual number of cells (or potatoes). The method is robust in that it is relatively insensitive to section thickness, sample size, somal morphology, and observer error with respect to missing the small or thin profiles from any given cell. Results from the present model are compared to those obtained by using other cell count correction schemes that are currently employed. We call our method recursive translation.
A horseradish peroxidase study of the olfactory system of the frog, Rana esculenta
Authors: Kemali M. , Guglielmotti V. 
Published: January 2005

AbstractThe olfactory system of the frog Rana esculenta was studied by using horseradish peroxidase (HRP) tracing of axonal pathways. Injections of HRP were made in the main olfactory bulb (MOB), accessory olfactory bulb (AOB), anterior olfactory nucleus (AON), the amygdala (AMY), and in a zone of the leteral wall of the telencephalic hemisphere immediately posterior to the AOB. Projections from these sites are described and are generally similar to those obtained by degeneration methods. However, HRP reveals more extensive olfactory connections than previously reported. Ipsilateral, contralateral, and bilateral projections arc described. The MOB, AOB, and AON have ipsilateral connections to each other. The MOB and AOB have very different projections. The MOB and AON project via the habenular commissure (HC) to the contralateral medial wall of the telencephalon. Ipsilateral MOB fibers also terminate in this cell‐free zone where the medial forebrain bundle (MFB) originates. The AOB projects to the lateral cortex of the contralateral telencephalic hemisphere via the HC and also to the ipsilateral AMY and lateral forebrain bundle (LFB) from where some fibers project contralaterally. HRP injections in the AMY retrogradely fill cells in the ipsilateral AOB, two nuclei of the ipsilateral hypothalamus and a nucleus of cells caudal to the ipsilateral nucleus isthmi. Fibers are also labeled that project to the contralateral AMY. Few fibers were observed to decussate in the interpeduncular nucleus or optic chiasma. No olfactory fibers were found to project to the habenular nuclei, and no labeled neurons were found to project to the olfactory bulbs. No morphological asymmetry was observed qualitatively in the distribution of olfactory fibers in the two halves of the brain.
Development and distribution of substance P in the spinal cord and ganglia of embryonic and newly hatched chick: An immunofluorescence study
Authors: Du Fu , Charnay Yves , Dubois Paul 
Published: January 2005

AbstractThe development and distribution of substance P(SP) immunoreactivity were studied in the spinal cord and ganglia of embryonic and newly hatched chick by using the indirect immunofluorescence method. Substance P immunoreactivity was first detected in the spinal cord at embryonic stages 18–20 (incubation day 3). Before stage 32 (day 7), it was mainly found in regions corresponding to the dorsolateral funiculus and Lissauer's tract. Subsequently, SP fibers appeared in the dorsal horn. By stage 38 (day 11), they were demonstrated almost throughout the gray matter, but mostly in laminae I and II. During this period, however, many SP‐positive cells were found just ventral to the central canal at the thoracic level, although a few were also detected in other areas throughout the cord. In the white matter, very dense longitudinal SP fibers were observed in Lissauer's tract and the dorsolateral funiculus, where extremely dense plexuses of SP immunoreactivity were also detected around a group of nonimmunoreactive cell bodies. At later stages, no remarkable differences were noticed in the distribution of SP fibers, but the SP‐positive cells decreased gradually in number and disappeared after hatching. However, they reappeared following colchicine treatment. In the spinal ganglia, SP immunoreactivity appeared initially at stage 25 (day 4). It was mostly located in small neurons of the mediodorsal region. These cells also decreased in number from later stages but increased by colchicine treatment after hatching. The development and distribution of SP immunoreactivity in the spinal cord and ganglia were generally comparable at all levels examined, except where indicated.