bluuebunny/crossref_metadata_2025_split huggingface dataset:
Derivation of cerebellar golgi neurons from the external granular layer: Evidence from explantation of external granule cells in vivo
Authors: Hausmann Beate , Mangold Ulrich , Sievers Jobst , Berry Martin 
Published: January 2005

AbstractThe present report provides evidence to challenge the traditional view that cerebellar Golgi cells are derived from the ventricular neuroepithelium, postulating instead that they originate from external granule cells. Supporting evidence for this assertion comes from three sources: (1) Typical Golgi cells are found in ectopic granule cell colonies, both outside the cerebellum (in the subarachnoid space) and also within the cerebellar cortex between fused folia. Because ectopic granule cell colonies are derived from external granule cells, which become displaced after treatment with 6‐hydroxydopamine (6‐OHDA), it was assumed that the ectopic Golgi cells also stem from such displaced external granule cells. (2) In order to demonstrate that Golgi cell precursors migrate from the external granular layer into the Purkinje cell plate, the development of the cerebellar cortex was studied over the period of Golgi cell genesis. On E19 the external granular layer in the rat is subdivided into an outer proliferative and an inner subproliferative zone. At the inner margin of the external granular layer, and in the marginal zone, radially oriented, darkly staining cells are present that exhibit all the characteristics of migrating neurons possessing a leading process oriented toward the Purkinje cell plate, a somatic cilium, and a close association with radial glia fibers. In later stages, these cells are also found deep to the Purkinje cell plate. Because Golgi cells arise during the period between E19 and postnatal day 2 in the rat (Altman and Bayer, 1977, 1978) and as the basket cells, the first neurons of proven origin from the external granular layer, are not produced before the second postnatal day (Altman, 1972), the earlier migrating neurons are presumed to be Golgi cells. (3) Available data from cell kinetic 3H‐thymidine studies show that there is no unequivocal evidence for Golgi cell genesis from the ventricular neuroepithelium, because, at the time of Golgi cell birth, ventricular and external granular stem cell populations are proliferating, and with the present methods it is not possible to decide which of these are the precursors of Golgi cells. Thus, taken together, the findings of this study show that Golgi cells are more likely to arise from the external granular layer than from the ventricular neuroepithelium. This concept would unify cerebellar histogenesis by proposing that projection neurons arise from the ventricular neuroepithelium, whereas all interneurons of the cerebellar cortex are descendants of the external granular layer.
The three‐dimensional morphology of afferent terminal fields in the rat dentate gyrus: Periodic variation
Authors: King Michael A. , Reep Roger L. , Hunter Bruce E. , Walker Don W. 
Published: January 2005

AbstractThe laminated afferent terminal fields in the rat dentate gyrus molecular layer exhibit differential histochemical staining properties. Dependent variables (e.g., field geometries, stain intensity) based on this organization can allow evaluation of the effect of independent variables upon the integrity of each afferent, but anatomically justifiable procedures for matching measurement regions across animals are necessary. We describe such a procedure and a serendipitous observation on the normal organization of the terminal fields. From a 10 × 10 mediolateral × anteroposterior array of measurement points per animal, it was determined that each afferent field, and the total molecular layer, exhibits periodic variation in width relative to the granule cell layer. Thus, to reduce statistical variability, either a high dependent variable sampling rate, or sampling within a region of naturally low variability, is suggested. Evidence for such a region is presented, and possible consequences of this novel topology of afferentation are discussed.
Postnatal development of the ipsilateral retinocollicular projection and the effects of unilateral enucleation in the golden hamster
Authors: Insausti R. , Blakemore Colin , Cowan W. Maxwell 
Published: January 2005

AbstractAnterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) was used to study the normal development of the ipsilateral retinocollicular projection in golden hamsters, and to examine the effect of enucleation of the other eye at birth. In neonatal animals there were retinal fibers and sparsely distributed granular labeling in the superficial layers of the ipsilateral superior colliculus over its entire areal extent. Differences in the uncrossed projections of normal and enucleated animals first became clear at day 5. In normal animals, retinal fibers withdrew from the superficial layers of the superior colliculus, and the projection became concentrated in the stratum opticum, where denser clumps of label in the rostral part of the superior colliculus were first seen at day 5. In enucleated animals, the retinal projection persisted in the most superficial layers, and the density of labeling was higher than in normals. The very sensitive WGA‐HRP technique showed retinal fibers extending to the caudal pole of the superior colliculus at all ages: even in normal animals more than 2 weeks of age some fibers reached as far as the inferior colliculus. When the shrunken size of the superior colliculus in the enucleated animals was taken into account, the total areal distribution of the ipsilateral projection was similar in normal animals and enucleates. The major difference between the two groups was in the higher density of ipsilateral labeling, especially in the caudal part of the superior colliculus, and in its more superficial laminar distribution in the enucleated animals.
The spinal terminations of single, physiologically characterized axons originating in the pontomedullary raphe of the cat
Authors: Light Alan R. 
Published: January 2005

AbstractSingle myelinated axons were recorded in the dorsolateral funiculus of the cat and physiologically characterized as descending from the midline medulla or midline pons. Following further physiological characterization (e.g., conduction velocity, adequate stimulus, receptive field, activation by stimulation of periaqueductal gray), the axons were Labeled with horseradish peroxidase that was iontophoretically ejected from the recording micro‐pipette. Histochemical reaction allowed visualization of the stained axons and their arborizations in the spinal gray matter. The conduction velocities of the sampled axons ranged from 7.3 to 117.2 m/second with a mean of 35.5 m/second. However, unmyelinated axons could not be sampled with the technique employed here. Descending axons could be divided into two groups: (1) those which terminated in laminae I, II, V, and X, and (2) those which terminated in laminae V, VII, and X. Axons from both groups had myelinated parent axons, were activated by periaqueductal gray stimulation, and responded to noxious pinch of their receptive field Terminal collaterals from both groups of axons were generally transversely oriented. These results suggest heterogeneous functions for these descending axons which may include modulation of nociceptive input to higher centers.
The ultrastructure and synaptic connections of the spinal terminations from single, physiologically characterized axons descending in the dorsolateral funiculus from the midline, pontomedullary region
Authors: Light Alan R. , Kavookjian Anahid M. 
Published: January 2005

AbstractSingle axons descending in the spinal, dorsolateral funiculus which were directly activated by stimulating in or near nucleus raphe magnus (nRM) in the rostral medulla were iontophoretically injected with horseradish peroxidase (HRP).Labeled axons and terminal arborizations in the spinal cord were demonstrated by diaminobenzidine histochemistry following fixation. Sections were processed for electron microscopy and embedded between coverslips. Following examination with the light microscope, selected boutons were sectioned in ultrathin series and examined with the electron microscope. Two arborization patterns were observed with the light microscope. One terminated dorsally in laminae I, II, V, and X, while the other terminated ventrally in laminae V, VII, and X.At the ultrastructural level, boutons predominantly contacted dendrites and occasionally contacted cell somas. Ventrally projecting axons had boutons characterizable as Gray's type I. Some dorsally projecting axons also had Gray's type I boutons, while other axons had Gray's type II boutons. Thus, these descending axons may be heterogeneous in function. No differences in physiological characteristics were found between axons with Gray's type I boutons versus axons with Gray's type II boutons.
The differential projection of two cytoarchitectonic subregions of the inferior parietal lobule of macaque upon the deep layers of the superior colliculus
Authors: Lynch J. C. , Graybiel A. M. , Lobeck L. J. 
Published: January 2005

AbstractParietotectal projections were studied in the macaque monkey in experiments designed to compare the distribution of fibers originating in two cytoarchitecturally distinct regions within the inferior parietal lobule: the inferior bank of the intraparietal sulcus (area POa of Seltzer and Pandya, '80) and the adjoining part of area PG (von Bonin and Bailey, '47) on the convexity of the hemisphere, here called PGc. A dense fiber projection from POa to the intermediate and deep layers of the superior colliculus was observed by both anterograde autoradiographic and anterograde horseradish peroxidase methods. In contrast, only faint labeling was seen in the superior colliculus following injections of tritiated amino acids into area PGc on the convexity. In a second set of experiments, injections of horseradish peroxidase were placed in the intermediate and deep layers of the superior colliculus so that the cells of origin of the parietotectal projections could be identified. Many retrogradely labeled neurons were observed in POa, whereas very few labeled neurons were present in any other subdivision of the inferior parietal lobule or in the superior parietal lobule. These findings demonstrate that area POa has a prominent direct efferent projection to a major premotor region of the brainstem oculomotor system and suggest that by virtue of its parietotectal connection, this sulcal subdivision may have functional properties not shared with other subdivisions of the inferior parietal lobule.
Peripheral nerve grafts to the frog optic tectum: A morphological study of foreign axon regeneration in the central nervous system
Authors: Kaplan Elliot I. , Clemente Carmine D. 
Published: January 2005

AbstractThe proximal stump of a transected mandibular nerve was grafted onto the rostrodorsal surface of the optic tectum in adult Rana pipiens to investigate the morphologic characteristics of nonspecific axonal regeneration in a highly organized region of central nervous system (CNS). Within the first 3 weeks postgraft surgery (WPS), the nerve‐tectum interface became firmly established. Concomitant with this was an invasion of the host tectum by a small number of fine “pioneerlike” axons from the nerve. By 6 WPS there developed a concerted instreaming of a large number of peripheral fibers. Once within the CNS, the foreign axons distributed themselves throughout the rostrocaudal extent of the tectum, but primarily its dorsal aspect within superficial layers 8 and 9.Presence of intact optic fibers at the time of mandibular fiber invasion served somewhat to restrict the regenerating aberrant axons in their course through layer 9. This restriction could be avoided by removal of the optic input either before or during peripheral ingrowth. However, once peripheral fibers had entered and established themselves in the host environment, no subsequent manipulation of the retinotectal projection had any effect.The aberrant growth pattern, which appeared remarkably stable after 6 WPS, consisted of a plexus of medium‐ and fine‐caliber peripheral axons. Many of these fibers had numerous branches and “en passant” varicosities, the latter encompassing a variety of shapes and sizes. Terminal swellings and arborizations were also found.When comparing the regeneration of optic and mandibular nerve fibers in the tectum, two distinctions were made. Whereas optic axons revealed a fascicular and layered organization, mandibular axons showed a highly segregated and disordered growth pattern. These characteristic differences were maintained even when the two fiber systems were allowed to coregenerate into the same target tectum. Thus, each of the two groups of axons interacts with the tectal substrate in a distinct manner, apparently independent of the other.
A reticular pattern of intrinsic connections in primate area V2 (area 18)
Authors: Rockland Kathleen S. 
Published: January 2005

AbstractA system of periodic intrinsic connections is demonstrated in area V2 (area 18) of squirrel and macaque monkeys by large injections of tritiated amino acids, horseradish peroxidase (HRP), and fluorescent latex beads. These connections originate from pyramidal neurons concentrated in layers 3 and 5. Terminations occur in all cortical layers, largely coextensive with labeled neurons but more restricted in layer 4. This multilaminar distribution contrasts with the mainly supragranular localization of periodic intrinsic connections in V1 (area 17), and may imply a close interaction, in V2, of periodic intrinsic connections with pulvinocortical, as well as with corticocortical terminations (concentrated, respectively, in layers 3 and 5, and in lower 3 and 4). As in V1, the tangential configuration of these connections in V2 is reticular or latticelike, and is detectable for 2.5–3.0 mm from an injection site of HRP, 3H amino acids, or latex beads. Cross‐sectional widths of labeled regions vary from 250 to 800 μm in squirrel monkey and from 400 to 1,000 μm in macaque, depending on which portion of the lattice is measured. When periodic intrinsic connections are compared with stripes labeled histochemically by cytochrome oxidase (CO), no clear relationship is obvious between the two systems. This result contrasts with the orderly tangential alignment reported between CO‐reactive zones in V2 and certain extrinsic connections; namely, pulvinocortical terminations (Livingstone and Hubel, '82) and clusters of neurons projecting to area V4 (DeYoe and Van Essen, '84). Other extrinsic connections, however, such as backgoing connections from V2 to V1, do not seem to have a periodic distribution. Thus, although some discontinuous cortical connections relate to each other in a precise mosaic fashion, intrinsic and some extrinsic connections may observe different modes of organization.
Functional organization of the cochlear nucleus of rufous horseshoe bats (Rhinolophus rouxi): Frequencies and internal connections are arranged in slabs
Authors: Feng Albert S. , Vater Marianne 
Published: January 2005

AbstractThe functional organization of the cochlear nucleus (CN) was studied with physiological recording and anatomical tracing techniques. Recordings were made from single CN neurons to examine their temporal firing patterns to tone burst stimuli and their frequency tuning characteristics. Recording loci of individual neurons were carefully monitored in order to understand how the functional properties of a cell relate to its location within the CN. We found that tonal frequencies were systematically represented in each of the three CN divisions (anteroventral, AVCN; posteroventral, PVCN; dorsal, DCN). Eight temporal response patterns were observed in CN neurons when stimulated at units' best excitatory frequencies (BF). With a few exceptions, neurons in each CN division could generate all eight firing patterns with different distributions for the three divisions. A focal injection of horseradish peroxidase (HRP), at the end of the physiological study, to a group of neurons possessing a similar BF in one CN division resulted in anterograde labeling of nerve terminals in the other two divisions at precisely the areas where the same frequency band was processed in these divisions. Labeled terminals in each division were closely congregated in the form of a thin slab. The slab orientation was division specific whereas its location was frequency specific, which could be predicted on the basis of physiological data. HRP injections into the DCN also resulted in retrograde labeling of somata in the AVCN and PVCN. On the other hand, only DCN neurons were retrogradely labeled when HRP was injected into the AVCN or the PVCN. These data showed how the three CN divisions are internally connected. Furthermore, retrogradely labeled cells occupied the same slabs where we found anterogradely labeled nerve terminals. Additionally, in a group of bats, HRP was injected into various functionally (i.e., BF) identified regions of the central nucleus of the inferior coliculus (IC) to clarify the type and location of CN projecting neurons. Retrogradely labeled cells in individual CN divisions likewise were arranged in slabs whose locations in the CN nuclei depended on the BFs of neurons at the injection site in the IC. These results show that slabs represent units of functional organization (i.e., tonal frequency, local connection and central projection) in the CN.
Reexamination of photoreceptor‐bipolar connectivity patterns in carp retina: HRP‐EM and golgi‐EM studies
Authors: Saito Takehiko , Kujiraoka Toru , Yonaha Tomohide , Chino Yuzo 
Published: January 2005

AbstractOn‐ and off‐center bipolar cells were identified in the carp retina by means of intracellular recording, intracellular injection of HRP, and Golgi silver‐chromate impregnation. Light and electron microscopy revealed that these functionally different bipolar cells make synaptic contacts with both rods and cones, and that both on‐ and off‐center cells can be further divided into two subtypes (I and II) according to the relationship between the position of their dendritic processes and the synaptic ribbons in the photoreceptor terminal. The type I on‐center bipolar cell is characterized by a large cell body, a thick primary dendrite, and a big swelling of the axon terminal in the innermost part of the inner plexiform layer (IPL). Dendritic processes of this cell type make predominantly ribbon contacts with rods and nonribbon contacts with cones. The type II on‐center cell, having a large dendritic tree in the outer plexiform layer and a large ramification of the axon terminal extending over the inner part of the IPL makes mostly nonribbon contacts with rods and cones. Many of these type II cell processes, however, terminate very close to cone synaptic ribbons. The type I off‐center cell shows two varieties in the axon terminal structure; a large terminal swelling or a large flat ramification of the terminal in the outermost part of the IPL. These cells make predominantly ribbon contacts with rods and cones. Usually, but not always, the process of a type I off‐center cell runs parallel to the synaptic ridge apex of cones. The type II off‐center cell, showing a large ramification of the axon terminal extending over the outer half of the IPL, makes mainly nonribbon contacts with rods and cones. The results from the HRP‐EM study generally agree with those from the Golgi‐EM study. A few discrepancies between the results obtained with these two techniques are noted and their implication is discussed.
Torpedo electromotor system development: Neuronal cell death and electric organ development in the fourth branchial arch
Authors: Fox Geoffrey Q. , Richardson Guy P. , Kirk C. 
Published: January 2005

AbstractThe fourth branchial arch of Torpedo marmorata has been examined at the light and electron microscopic level during development. Of interest was the determination of the extent of electric organ tissue reported to be present in this arch and its possible relationship to electromotoneuron cell death in the electric lobes. The main electric organ of the torpedo is derived from the hyoid and first three branchial arches and is innervated by four major electromotor nerves. Extensive electromotoneuron cell death occurs in the electric lobes and most notably in the posterior poles. This feature could be due to a tendency for these neurons to innervate the fourth branchial arch where little or no electric tissue is formed. Our findings support this conclusion but are not entirely consistent with the idea that a population mismatch has occurred. This is because cell death precedes the genesis of the target cells. The presence of innervated differentiated electric tissue in this arch is also reported, leading to the conclusion that Torpedo marmorata possesses an accessory electric organ.
Distribution of certain peptide‐containing nerve fibres and endocrine cells in the gastrointestinal mucosa in five mammalian species
Authors: Keast J. R. , Furness J. B. , Costa M. 
Published: January 2005

AbstractThe distribution of mucosal nerve fibres containing vasoactive intestinal peptide (VIP), substance P, somatostatin, neuropeptide Y (NPY), and enkephalinlike immunoreactivity was mapped by conventional immunohistochemical techniques throughout the mucosa of the esophagus, stomach, small and large intestines, and gall bladder. In addition, the distributions of endocrine cells immunoreactive for three peptides localized by these antisera (namely somatostatin, pancreatic polypeptide, and substance P) were recorded. Tissues from guinea pigs, rats, dogs, marmosets, and humans were studied. It was hoped that this information would enable possible target tissues and functional roles for the peptides to be identified.In the mucosa, peptide nerve fibres were found throughout the lamina propria, including some which were close to the epithelium and others associated with small blood vessels. Although there was a general similarity of peptide nerve distribution between regions and species, many small variations were observed. VIP and substance P fibres were the most prevalent nerve type; NPY fibres were also usually quite common. The distribution of somatostatin fibres was extremely variable between regions and species, and enkephalin fibres were usually rare. Endocrine cells of open (flask‐or pyramid‐shaped) and closed (rounded) types were seen; basal cytoplasmic processes (of variable length) were seen on many cells immunoreactive for somatostatin or pancreatic polypeptide. Epithelial cells immunoreactive for substance P were seen in the dog, marmoset, and human. The distributions and shapes of endocrine cells varied widely between areas and species.These studies provide a basis for the correlation of nerve distribution with pharmacological and physiological studies.
The distribution of somatostatin‐like immunoreactivity in the monkey hippocampal formation
Authors: Bakst I. , Morrison J. H. , Amaral D. G. 
Published: January 2005

AbstractThe distribution of somatostatin‐Like immunoreactivity was studied in the hippocampal formation of the Old World (Macaca fascicularis) and New World (Saimiri sciureus) monkeys. Series of coronal sections were processed by the unlabeled second antiserum method using primary antisera which recognize somatostatin‐28 (S309) or somatostatin‐281–12 (S320). Neuronal cell bodies were more readily stained with antiserum S309 and were observed throughout the hippocampal formation. The most prominent accumulations of stained neurons occur in the hilar region of the dentate gyrus, in strata oriens and pyramidale of regio inferior of the hippocampus, and in the deep layers of the entorhinal cortex. Both antisera demonstrated extensive fiber systems which varied in density regionally in the hippocampal formation. Stained fibers were most prominent in the outer two‐thirds of the molecular layer of the dentate gyrus, in stratum lacunosum‐moleculare of the hippocampus, in layer I of the presubiculum and in layers I, III, and V of the entorhinal cortex.