bluuebunny/crossref_metadata_2025_split huggingface dataset:
An HRP study of the relation between cell size and motor unit type in cat ankle extensor motoneurons
Authors: Burke R. E. , Dum R. P. , Fleshman J. W. , Glenn L. L. , Lev‐Tov A. , O'Donovan M. J. , Pinter M. J. 
Published: January 2005

AbstractThe dimensions of the somata and stem dendrites of 57 α‐ and three γ‐ motoneurons, identified as to motor unit type and labeled by intracelluar injection of horseradish peroxidase, were measured in the triceps surae and plantaris motor pools. The somata of type S motoneurons tended to be smaller (mean diameter 47.9 μm) than those of FF and FR units (52.5 and 53.1 μm, respectively) but these mean values were not significantly different and the data distributions showed considerable overlap between the unit types. The mean numbers and diameters of stem dendrites of stem dendrites exhibited somewhat larger differences related to motor unit type and some of these were statistically significant. The total membrane area (AN) of each cell was estimated from measurements of the soma and stem dendrites, by using recent data of Ulfhake and Kellerth ('81) to calculate the membrane area of a dendritic tree from stem dendrite diameter. Mean AN varied with motor unit type in the sequence FF > FR > S (average values: 369 × 1003 μm2, 323 × 1003 μm2, and 250 × 1003 μm2, respectively). There was covariation between AN and the conduction velocity of the motor axon, as well as with the force output from the muscle unit. Comparison of AN and motoneuron input resistance (RN) in 19 α‐motoneurons suggested that the specific resistivity of the cell membrane in type S motoneurons was systematically higher than that characteristic of type FF or FR motoneurons.
Topography between the entorhinal cortex and the dentate septotemporal axis in rats: I. Medial and intermediate entorhinal projecting cells
Authors: Ruth Russell E. , Collier Timothy J. , Routtenberg Aryeh 
Published: January 2005

AbstractRetrograde tracing experiments were performed to clarify the topographic projection from medial (area 28m) and intermediate (area 28i) divisions of the entorhinal cortex to the dentate gyrus. Pipets filled with horseradish peroxidase (HRP) were positioned by electrophysiologic guidance at one of several septotemporal (S‐T) levels in the dentate molecular layer of anesthetized rats; the tracer was expelled iontophoretically to minimize its spread. Retrograde labeling of neurons within areas 28m and 28i was analyzed in relation to cytoarchitectonic as well as spatial features of the region (obtained by histologic reconstruction).Regardless of the S‐T level, ejections of HRP which were confined to the dentate gyrus labeled only layer II neurons of each area. Following septal pole ejections, labeled neurons were located in the posterolateral, extreme posterior, and postermedial parts of both areas 28m and 28i. Mid S‐T ejections produced not only a ventral, but also an anteromedial, shift in the location of entorhinal projection cells; no cells were labeled posterolaterally. After temporal dentate ejections labeled neurons occupied the most anteromedial part of these entorhinal areas. For both areas, but especially for area 28i, convergence of entorhinal efferents upon a single S‐T level in the dentate gyrus occurred from neurons which lay in a dorsoventral (i. e., frontal), and to a lesser extent a rostrocaudal, plane.The efferent axes of both areas 28m and 28i thus appear to be curved and are therefore best described in three dimensions. The entorhinal axes begin in a posterodorsolateral location, wrap around the posterior cortical convexity, and end in an anteroventromedial position. The results provide a useful map for in situ exploration of entrohinodentate connections in the rat, emphasize the parallel innervation of the dentate gyrus by distinct entorhinal fiber systems, and reflect the importance of the S‐T axis as a framework for interpreting hippocampal organization.
The distribution and origin of serotonin‐containing fibers in the septal area: A combined immunohistochemical and fluorescent retrograde tracing study in the rat
Authors: Köhler Christer , Chan‐Palay Victoria , Steinbusch Harry 
Published: January 2005

AbstractThe distribution of 5‐hydroxytryptamine (serotonin, 5‐HT)‐containing nerve fibers and terminals in the septal area of the rat was studied by using immunohistochemistry with specific antibodies to 5‐HT in combination with fluorescent retrograde tracing methods. The 5‐HT innervation of the septum is heterogeneous with regard to both the morphology of individual processes and the density of distribution in different parts of the septum. Three major classes of 5‐HT like immunoreactive processes can be distinguished: (1) thin, convoluted fibers with small, round or elongated varicosities; (2) thick and relatively straight fibers with few varicosities; and (3) pericellular plexuses with large varicosities in close association with perikarya in the lateral septum. Three areas of the septum receive a prominent innervation by 5‐HT processes: the diagonal band of Broca, the ventral part of the lateral septum, and and area bordering the medial edge fo the islands of Calleja (insula magna). Whereas the two latter areas contain dense terminal networks, the diagonal band of Broca is occupied primarily by 5‐HT fibers en route to other parts of the septum. Intraseptal injections of HRP or fluorescent dyes (granular blue, propidium iodide) resulted in retrograde labeling of neuronal cell bodies in several nuclei of the brainstem which are known to contain 5‐HT neurons: the dorsal raphe, the median raphe, the nucleus reticularis tegmenti pontis, the raphe pontis, and the raphe magnus. Where fluorescent retrograde tracing was performed with 5‐HT immunohistochemistry on the same tissue section, a prominent 5‐HT containing pathway and a non‐5‐HT‐containing pathway from the raphe nuclei to the septum were revealed. Finally, double retrograde fluorescent labeling after injections of granular blue or propidium iodide into the septum and entorhinal area respectively of the same rat revealed extensive branching of the raphe efferents. Thus, individual raphe neurons may simultaneously connect with septum and the entorhinal area, two structures essential for normal hippocampal function.
The efferent connections of the nucleus of the optic tract and the superior colliculus in the rabbit
Authors: Holstege Gert , Collewijn Han 
Published: January 2005

Abstract3H‐leucine injections were made in tectal and pretectal areas in the rabbit. After injections in the nucleus of the optic tract (NOT) labeled fibers were distributed bilaterally to the superior colliculus, the dorsal part of the medial geniculate nucleus (MGd), and the pulvinar nucleus, and ipsilaterally to the external layer of the ventral lateral geniculate nucleus (LGv), the dorsal geniculate nucleus (LGd) pars β, the reticular thalamic nucleus, and the lateral and medial terminal nucleus (LTN, MTN). Many labeled fibers were distributed to the lateral and some to the medial parts of the pontine nuclei. More caudally, coarse labeled fiber bundles descended ipsilaterally, distributing fibers to the prepositus hypoglossi and abducens nucleus and to the caudally adjoining medial reticular formation. Many labeled fibers were also present in the inferior olive, especially ipsilaterally in the dorsal cap and the ventrally adjoining pars β, and a few in the contralateral dorsal cap area. Contralaterally, some descending fibers terminated in the dorsal part of the facial nucleus, in which motoneurons are located innervating the orbicularis oculi muscle.The superficial layers of superior colliculus distributed fibers bilaterally to the internal layer of the ventral lateral geniculate nucleus (LGv), the LGdα (lateral part), the MGd, the pulvinar, and more caudally to the ipsilateral parabigeminal and lateral pontine nuclei.The deep collicular layers distributed fibers ipsilaterally to MG (internal division), pulvinar, and the internal layer of LGv. Furthermore, ascending connections were found to the suprageniculate nucleus, the zona incerta, the mediodorsal nucleus, and some intralaminar and midline nuclei. Descending fibers terminated in the mesencephalic lateral tegmentum, pontine nuclei, and ventrally in the pontine and high medullary reticular formation. Contralaterally fibers were distributed to the nucleus reticularis tegmenti pontis (NRTP), the medial reticular formation, and the inferior olive just lateral to the nucleus β. In one case fibers were also distributed to the lateral part of the contralateral facial nucleus in which motoneurons are located innervating the upper lip muscles.
Organization of nucleus rotundus, a tectofugal thalamic nucleus in turtles. III. The tectorotundal projection
Authors: Rainey W. T. , Ulinski P. S. 
Published: January 2005

AbstractNucleus rotundus is the primary thalamic recipient of projections from the optic tectum in pond turtles. Although the projection of the retina to the optic tectum is known to be topographically organized, earlier studies suggest that the tectorotundal projection is not topographically organized. Three types of analyses are used in this paper to characterize the organization of the projection of the optic tectum to nucleus rotundus.First, large iontophoretic injections of horseradish peroxidase into the optic tectum anterogradely fill axons with reaction product after the use of a cobalt‐enhanced diaminobenzidine procedure. These preparations show that shafts of axons in the tectothalamic tract give rise to thinner, primary collaterals that enter nucleus rotundus from its caudolateral aspect and form sparsely branching arbors within the nucleus. Very thin secondary collaterals branch from these collaterals bear terminal collaterals with frequent varicosities. Although the total size of such arbors is unknown, the evidence suggests that each arbor is large in relation to the size of nucleus rotundus. Thus, injection sites restricted to central tectum label axons throughout nucleus rotundus. Second, subtotal lesions of the tectum produce degeneration throughout nucleus rotundus in silver degeneration preparations. Finally, analysis of electron microscopic degeneration material indicates that tectal boutons are distributed along the full lengths of the dendrites of rotundal neurons, but not on their somata. These boutons form asymmetric synaptic junctions and contain round synaptic vesicles.In view of the relatively large size of the dendritic fields of rotundal neurons, these data suggest that the tectorotundal projection is both strongly convergent on individual neurons and strongly divergent from single tectorotundal axons. This type of organization is consistent with physiological evidence that rotundal neurons have receptive fields that cover at least one‐half of the contralateral visual field and often include the entire hemifield. It seems unlikely that nucleus rotundus can be involved in neuronal transactions that preserve detailed spatial information, but it may be involved in processing information on other visual parameters such as stimulus velocity or color.
Exteroceptive and proprioceptive afferents of the trigeminal and facial motor nuclei in the mallard (Anas platyrhynchos L.)
Authors: Arends Joseph J. A. , Dubbeldam Jacob L. 
Published: January 2005

AbstractCentral pathways converging upon the trigeminofacial motor nuclei of the mallard were studied in order to elucidate neuroanatomically the presumed influence of primary sensory trigeminal afferents upon jaw muscle activity. The techniques used included the Fink‐Heimer I method after lesions, and axonal transport labeling following injections of 3H‐leucine or of HRP for retrograde identification of the neurons of origin.A general description is given of the trigeminofacial motor complex. Jaw closer muscles are innervated by trigeminal motor neurons, and facial motor neurons innervate the jaw depressor muscles. Two afferent premotor systems, one including the mesencephalic trigeminal nucleus (MesV) and the other the rhombencephalic reticular formation, are distinguished. The proprioceptive neurons of the mesencephalic trigeminal nucleus project upon the ipsilateral trigeminal motor nucleus and upon the nucleus supratrigeminalis. The latter cell group bilaterally projects upon the dorsal and intermediate parts of the facial motor nucleus and upon part of the trigeminal motor nucleus. Exteroceptive information, relayed through the primary sensory trigeminal column (PrV and nTTD), ultimately reaches the motor nuclei via the reticular formation. The reticular formation forms the final link of three separate circuits: a telencephalic one entered through the principal trigeminal sensory nucleus, a cerebellar one via subnucleus oralis of the descending trigeminal system, and a direct one via subnucleus interpolaris. No direct connections between the principal trigeminal sensory nucleus or subnuclei of the descending trigeminal system and the motor nuclei of the trigeminal (NV) and facial (NVII) nerves have been observed, nor are such direct projections present in the outflow of the presumed telencephalic and cerebellar circuits, viz. of the archistriatum and the central cerebellar nuclei, respectively. The archistriatum projects via the occipitomesencephalic tract upon the lateral rhombencephalic reticular formation as far down as the rostral cervical cord, as well as upon the subnucleus interpolaris of the descending trigeminal system. Similarly, efferents from the central cerebellar nuclei reach the reticular formation, which in turn projects bilaterally upon the motor nuclei. Finally, commissural intermotor connections apparently are mediated by reticular cells surrounding the motor nuclei of NV or NVII, rather than emanating from these nuclei directly.
Light and electron microscopy of the photoreceptors in the retina of the red‐eared slider, Pseudemys scripta elegans
Authors: Kolb Helga , Jones Jill 
Published: January 2005

AbstractThe six different types of photoreceptor in the retina of the turtle Pseudemys scripta elegans have been studied by light and electron microscopy. Fresh whole‐mount retina, in which the oil droplet colors of the photoreceptors could be seen, was compared with fixed tissue cut in the vertical plane. The red single cone (large red oil droplet) is largest in diameter and, in electron microscopy (EM) views, has the least opaque oil droplet. It also has a vacuolated paraboloid and a cone pedicle that ends at the intermediate level of the outer plexiform layer (OPL). The green single cone (yellow medium‐size oil droplet) has a thinner inner segment and uniformly vacuolated paraboloid. Its cone pedicle ends at the same level as that of red cones. The blue cone (small colorless oil droplet) has an obliquely running axon joining cell body to cone pedicle that lies innermost in the OPL. Double cones are recognizable by their adherent cell bodies and inner segments. The accessory member (green cone) lacks an oil droplet but has a distinct large paraboloid while the principal member (red cone) has an oil droplet (orange) lying more distal than oil droplets of other cone types. The axons of the double cones are separated by glia but have closely apposed pedicles ending above those of the single cones in the outermost level of the OPL. Rod photoreceptors have a large outer segment, no oil droplet, and a lowlying cell body continuous with the pedicle, which ends, like those of the double cones, at the outermost level of the OPL.
Target regulation of synaptic number in the compressed retinotectal projection of goldfish
Authors: Murray Marion , Sharma Sansar , Edwards Michael A. 
Published: January 2005

AbstractIn order to determine the morphological consequences of the formation of a compressed retinotectal projection, the optic neuropil lamina (stratum fibrosum et griseum superficialis, SFGS) was examined in large goldfish 3 months to 4 years after ablation of the caudal half of the tectum, both with crush of the optic nerve (HTX) and without (HT). In semithin sections, the SFGS, as delineated with orthograde HRP labeling, shows a persistent hypertrophy of about 25% in HTX and HT groups. Comparison of ultrastructural stereological data with similar data on control and regenerated projections to intact tecta (Murray and Edwards, '82) indicates that this hypertrophy can be attributed largely to an increased number of axons and not to increases in terminal or dendritic compartments. A normal number of synaptic terminals per column through SFGS is conserved in HTX and HT groups. Planimetric analysis and observations using orthograde HRP labeling reveal no group differences in size and shape of terminal profiles. The same number of retinal ganglion cells project to a half‐tectum as to an intact tectum, as indicated by estimates of ganglion cell number and of the minimum percentage of them which project to the tectum using retrograde HRP labeling.The results suggest that the regenerating and sprouting optic axons participating in the formation of a compressed retinotopic projection compete for a limited accommodation in the SFGS and that this capacity to accept synaptic input becomes saturated at the control innervation density. The results are consistent with the formation of a smaller than normal number of terminals per optic axon, numerical estimates for which are given. If the percentage of terminals which are optic does not change, then the number of terminals per axon is reduced by about 40%.
Spinal cord development in anuran larvae: I. Primary and secondary neurons
Authors: Forehand Cynthia J. , Farel Paul B. 
Published: January 2005

AbstractThe spinal cord of the bullfrog (Rana catesbeiana) tadpole contains primary neurons, born during embryonic stages, and scondary neurons born for the most part during larval stages. Electrophysiological and anatomical characteristics of these two categories of neurons were examined during larval development to trace the development of secondary neurons and to determine whether primary neurons persist into adult life or are replaced by secondary neurons. Five classes of primary neuron were identified on the basis of their distinctive locations, morphologies, cytoplasmic melanin content, and presence at the earliest larval stages examined: primary motoneurons, Rohon‐Beard cells, commissural cells, dorsal marginal cells, and anterolateral marginal cells. Secondary neurons of the lateral motor column and dorsal root ganglia underwent extensive developmental changes during larval life manifested both in anatomical studies with horseradish peroxidase and electrophysiological experiments on the isolated spinal cord. Primary motoneurons that innervate the tadpole tail were not found in the adult, although those innervating thoracic musculature persisted, as did at least some primary neurons projecting to other spinal segments or brainstem. Primary neurons are thus replaced or maintained through metamorphosis depending on their class and location.
Influence of neonatal cochlear removal on the development of mouse cochlear nucleus: I. Number, size, and density of its neurons
Authors: Trune Dennis R. 
Published: January 2005

AbstractRight cochleae were aspirated from 6‐day‐old mice to determine the influence of cochlear integrity on the development of cochlear nucleus (CN). At 45 days of age, cochlear destruction was confirmed histologically, and the CN of unilaterally deafferented and control animals were analyzed morphometrically. The molecular, fusiform, and polymorphic layers of deafferented dorsal CN were reduced in volume, and the polymorphic layer neurons were fewer, smaller, and less dense. The octopus and multipolar cell regions in deafferented ventral CN (VCN) were smaller, and their neurons were fewer, smaller, and more densely packed. The VCN globular and small spherical cell regions were also smaller with fewer, denser, but normal‐sized neurons. There were fewer VCN large spherical cells, but no change was measured in their size. The granule cell regions throughout CN were also reduced in volume. Overall, CN was reduced to 46% of its normal size and 34% of its normal neuronal numbers. These results in the mouse show that deafferentation before the onset of hearing causes more severe CN changes than those reported after adult deafferentation in other mammals and support the theory of a critical period in development when presynaptic integrity is much more important for neuronal maturation than it is for maintenance after the neuron is mature. This suggests that any congenital pathology that compromises the sensorineural structures of the cochlea may cause severe structural and functional abnormalities in the maturing central auditory nuclei.
Retinofugal pathways in juvenile and adult channel catfish, Ictalurus (Ameiurus) punctatus: An HRP and autoradiographic study
Authors: Rao P. D. Prasada , Sharma S. C. 
Published: January 2005

AbstractThe retinal projections of the juvenile and adult channel catfish, Ictalurus (Ameiurus) punctatus, were studied by using horseradish peroxidase (HRP) and autoradiography. The contralateral optic tract sends fibers to the suprachiasmatic nucleus (SCN) and divides into lateral (LOT) and medial optic tracts (MOT). In the adult fish, the former is thicker than the latter, whereas in the juvenile form, the reverse is true. The MOT curves laterally and divides into eight to 15 medial fascicles of the optic tract (MFOT). The contralateral optic fibers project to the nucleus opticus dorsolateralis, nucleus of the posterior commissure, nucleus geniculatus lateralis, pretectal nuclear complex, nucleus corticalis, stratum fibrosum et griseum superficiale (SFGS), and a few optic fibers extend into the stratum griseum centrale. The tractus opticus accessorius arises from the postero‐dorsal margin of the LOT and extends ventromedially to project to the nucleus opticus accessorius. At the optic chiasm a few fibers do not decussate, and these fibers project to almost all ipsilateral sites similar to those of the contralateral side, including the optic tectum. The autoradiographic observations substantiated the analysis of optic fiber projections provided by the HRP technique.