bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ipsilateral afferents to the commissural zone of the fascia dentata, demonstrated in decommissurated rats by silver impregnation
Authors: Zimmer Jens 
Published: December 2004

AbstractAn ipsilateral pathway to the commissural zone of the dentate fascia has been demonstrated in the rat using the Fink‐Heimer silver impregnation method. The pathway arises in one or both of the CA3c and CA4 hippocampal subfields. As lesions of these structures normally will cause degeneration of commissural fibers terminating in the dentate fascia, animals without commissural fibers were provided for this study. This was done by transecting the hippocampal commissures in eight day old rats which were allowed to survive until the adult stage at which time all stainable, degenerating commissural fibers had disappeared. Lesions involving the CA3c/4‐subfields were then made. The resulting degeneration in the commissural zone of the dentate fascia was shown to be of purely ipsilateral origin.Fibers of this pathway display a spread along the longitudinal septotemporal axis of the hippocampal formation. The spread in the “septal” direction (ascent) is in general greater than the descent in the temporal direction, and the more “septal” the lesion is placed, the further does the degeneration extend in the septal direction. The most ascending fibers occupy a juxtagranular position along the medial crus of the dentate granule cells. The most descending (temporal) fibers are seen superficially in the commissural zone along the lateral crus.The pyramids of CA3c and the modified pyramids of CA4 are considered the most probable cells of origin of this system.The ipsilateral system may possibly be absent in normal rats. In view of the early age at which decommissuration was carried out in the experimental animals, axonal sprouting, resulting in the appearance of fibers which may normally be absent, cannot be excluded.
The red nucleus of the opossum (Didelphis marsupialis virginiana): A light and electron microscopic study
Authors: King James S. , Bowman Michael H. , Martin George F. 
Published: December 2004

AbstractThe opossum midbrain was sectioned in frontal, sagittal and horizontal planes and subsequently stained with cresyl violet to determine the cytoarchitecture of the red nucleus. The neurons were visualized in more detail in Golgi preparations, one micron plastic sections and by employing electron microscopy.Distinct parvicellular and magnocellular subdivisions are not apparent in this species. The characteristic neurons can be divided into three types by utilizing the following criteria: size, distribution of Nissl bodies and dendritic patterns. The cytoplasm of the giant neurons (45–70 μ) is filled with Nissl granules and the dendrites are long and tapered, and display an occasional spine. The large‐medium neurons (40–25 μ) can be differentiated from the giant neurons on the basis of size and their less extensive pattern of dendritic branching. Small neurons (10–20 μ) are achromatic or have a uniformly basophilic cytoplasm and may be classified as Golgi type II neurons.The large‐medium size neurons are the most numerous of the three types described and they are distributed throughout the entire extent of the nucleus. The small neurons, although found less frequently than the large‐medium size cells, also are scattered throughout the nucleus. The giant neurons are limited to the caudal medial 0.5 mm of the nucleus.A morphological classification of synaptic terminals is described: (1) small (1–2 μ), (2) elongate (up to 10 μ), (3) boutons en passage and (4) large (2–4 × 5–9 μ). Differences in the population of synaptic vesicles in the four types of synaptic endings are described. In addition, differences in the distribution of the four types of synaptic terminals with respect to the soma, proximal dendrites and dendrites in the neuropil are illustrated.
Projection of the cochlea to cochlear nuclei in merriam's kangaroo rat
Authors: Webster Douglas B. 
Published: December 2004

AbstractProjection of the cochlea onto the cochlear nuclei was studied by lesioning the spiral ganglion and tracing degenerating fibers and terminals by the Nauta‐Gygax and Fink‐Heimer methods. Basal turn lesions result in degeneration in the medial portion of anterior ventral cochlear nucleus (AVCN) including globular cell area, small spherical cell area, and a small portion of the large spherical cell area; in dorsomedial portion of posterior ventral cochlear nucleus (PVCN) including globular cell area and octopus cell area; and in the medial extreme of the central region of dorsal cochlear nucleus (DCN). Apical turn lesions result in degeneration in the lateral portion of AVCN including globular cell area, small spherical cell area, and a substantial amount of the large spherical cell area; in the ventrolateral portion of PVCN including globular cell area and multipolar cell area; and in the lateral extreme of the central region of DCN. Lesions in intermediate turns of the cochlea result in degeneration in correspondingly intermediate regions of the cochlear nuclear complex. The basal portion of the cochlea (high frequency) projects most strongly to the small spherical cell area and the octopus cell area. The apical turns (low frequency) project most strongly to the large spherical cell area and the multipolar cell area.
A comparison of somatotopic organization in sensory neocortex of newborn kittens and adult cats
Authors: Rubel Edwin W. 
Published: December 2004

AbstractTo determine the state of functional development in the newborn kitten's somatic sensory system, the organization of mechanoreceptive projections to the sensorimotor cortex was compared to that of the adult Cat. Microelectrode mapping procedures were used.Projections from all contralateral body surfaces to the primary somatomotor cortex (SmI) are present at birth and respond to mechanical stimulation of the receptors. The somatotopic organization of these projections in the newborn kitten is similar to that in the adult cortex with respect to the cortical region receiving projections from each part of the body and to the detailed arrangement of the projections within each of these cortical subdivisions.The relative sizes of peripheral receptive fields, and the intensity of stimulation effective for eliciting a response were similar for projections in SmI cortex of both kittens and adults. At both ages receptive field sizes decreased as their locations approached the distal portion of the limbs or rostral part of the face. In adults and newborns, over 75% of the neuronal responses were elicited by gentle bending of the hairs or light touch to the glabrous skin surfaces.Other similarities between adult and newborn sensorimotor cortexes included: (a) receptive fields of projections to SmI cortex were of fixed, local field type; (b) projections to SmII cortex responded to mechanical stimulation of the receptors; (c) ipsilateral as well as contralateral body surfaces were represented in SmII cortex; (d) the columnar arrangement of neurons and their receptive fields were apparent in the SmI cortex; (e) the coronal sulcus formed a division between the representations of the forepaw and face.Differences between newborn kittens and adult cats included: (a) shorter latency from electrical stimulation of the skin to a SmI cortical response in adults; (b) projections to SmI cortex having “disjunctive” receptive fields were not found in newborn kittens but existed in the adults; (c) the diversity of receptive field types found in neurons of the adult postcruciate MsI cortex was not found in newborn kittens; (d) newborn subjects displayed less variability in the somatotopic organization of projections and less overlap in the receptive fields of projections to SmI cortex.It is suggested that the SmI cortex develops as a point‐to‐point reflection of the distribution of mechanosensitive receptors in the body and that the complexities in this organization seen in the adult cortex occur during postnatal development.
A study of retrograde cell degeneration in the lateral mammillary nucleus of the cat, with special reference to the role of axonal branching in the preservation of the cell
Authors: Fry Francis J. , Cowan W. Maxwell 
Published: December 2004

AbstractThe significance of axonal branches in maintaining the integrity of the neuronal soma after axon section has been studied in the lateral mammillary nucleus (LMN) of the cat. Earlier studies with the Golgi and reduced silver methods have shown that the axons of most, if not all, of the cells of this nucleus which enter the principal mammillary tract (PMT) bifurcate with one branch entering the mammillo‐thalamic tract (MThT) and the other the mammillo‐tegmental tract (MTgT). Some of the fibers in the MThT may again bifurcate before ending bilaterally in the anterodorsal nucleus of the thalamus (AD).Unilateral destruction of the AD results in no detectable retrograde cell degeneration in the LMN. Lesions of the MThT (below the interanteromedial nucleus) cause a slight (∼ 15%) cell loss in the LMN, while isolated lesions of the MTgT have no detectable effect upon the cells of the nucleus. Combined lesions of the MThT and the MTgT cause severe retrograde degeneration in the LMN: approximately 60% of the cells disappear and many of the surviving neurons are frankly atrophic. Lesions of the PMT involving the parent axons of the cells in the LMN result in about the same degree of cell loss as combined lesions of the MThT and MTgT, but the persisting neurons are more severely shrunken and pyknotic.The implications of these findings for the organization of the connections of the LMN and for the interpretation of retrograde cell degeneration are discussed.
The fine structure of nerve fibers and endings in the lateral cerebral ventricles of the rat
Authors: Westergaard Erik 
Published: December 2004

AbstractThe brains of adult rats were fixed by vascular perfusion with glutaraldehyde. Tissue blocks were cut from the walls in the anterior horn of the lateral ventricles. The blocks were impregnated with uranyl magnesium acetate and embedded in Vestopal. Numerous nerve fibers lay supraependymally, singly or in groups, between the microvilli and cilia of the ependymal cells. Varicosities occurred along the fiber, often in close succession. The intraventricular nerve endings were flask‐shaped. Vesicles were present in the cytoplasm of the nerve processes, varying considerably in shape, size and content. They were round or flattened. Some contained a dense core, whilst others were more or less empty. A zonula adhaerens was sometimes observed between a nerve ending and the luminal plasma membrane of an ependymal cell.The present study and other studies are compatible with the concept that the intraventricular nerve processes are receptors, possibly registering the composition of the cerebrospinal fluid. A further possibility is that the nerve processes give off a secretion to the cerebrospinal fluid.
Supraoptic nuclei of rodents adapted for mesic and xeric environments: Numbers of cells, multiple nucleoli, and their distributions
Authors: Hatton Glenn Irwin , Johnson John Irwin , Malatesta Carol Zander 
Published: December 2004

AbstractQuantitative comparisons were made between the supraoptic nuclei (SON) of rodents from mesic and xeric habitats. Laboratory rats, Rattus norvegicus, mesically adapted, were compared with xerically adapted gerbils, Meriones unguiculatus, and kangaroo rats, Dipodomys merriami and Dipodomys spectabilis. As a close genetic control, California deer mice, Peromyscus californicus (mesic), were compared with cactus mice, Peromyscus eremicus (xeric), of the same subgenus. Measures were obtained separately for anterior (Soa) and tuberal (Sot) subdivisions of SON in each species; these measurements included numbers of cells, cell size and, following the discovery of multiple nucleoli in many cells, the proportion of cells showing 1, 2, 3, and 4 or more nucleoli. In mesic species, Sot had fewer cells than Soa; in all but one (D. spectabilis) of the xeric species, the two subdivisions had equal numbers of cells. Cell size was related to body size rather than adaptation. All xeric species showed higher proportions (20 to 60%) of cells with multiple nucleoli than did corresponding mesic species (0 to 20%). Adaptation to environments requiring conservation of body water is correlated with larger numbers of SON cells with multiple nucleoli; relatively larger numbers of cells in Sot but not in Soa; and there are no notable differences in size of cells between mesic‐ and xeric‐adapted species. The suggestion that number of nucleoli is realated to a SON cell's production of antidiuretic hormone is supported by other cytological studies.
The role of climbing fibers in the formation of Purkinje cell dendrites
Authors: Kornguth Steven Edward , Scott Grayson 
Published: December 2004

AbstractThe relationship of the climbing fibers to developing Purkinje cells in the cerebellums of fetal macaques at 75‐, 100‐, 125‐, and 150‐days after conception was studied using Golgi stains and electron microscopic techniques. Between 125 and 150 days of fetal life the somatic processes of the Purkinje cells were most prominent and the apical dendrites were in the initial stages of their development. Serial sections of Purkinje cells, in the cerebellums of 125‐day fetuses, were made and photographed in the electron microscope. Montages of individual Purkinje cells were prepared to permit tracing of the somatic processes and the climbing fibers. It was observed that Purkinje cells developed processes only after becoming associated with climbing fibers and that the climbing fiber terminals capped the growing ends of the processes at this critical stage. In several cases, growing tips of these processes penetrated the terminal boutons. The fine structure of the synaptic junction between the climbing fiber terminal and the Purkinje cell was analyzed using stereo‐electron micrographs (× 125,000). From these observations and those of other authors it was concluded that the climbing fiber induces the formation of somatic processes which then develop into the elaborate dendritic tree. Furthermore, it is proposed that synaptic connections have contractile properties, and that it is this contractility which induces dendrite elaboration.
The distribution of autonomic nerves in the musculature of the rat vas deferens. A light and electron microscope investigation
Authors: Dixon J. S. , Gosling J. A. 
Published: December 2004

AbstractLight microscope histochemical techniques and electron microscopy were used to study the distribution of autonomic nerves in the muscle coat of the rat vas deferens. Numerous fluorescent catecholamine containing nerves were demonstrated throughout the length of the vas; muscle cells on its inner aspect were particularly well innervated. This distribution differed markedly from that of acetylcholinesterase containing fibres, the majority of which occurred at the testicular end. Few similar nerves were observed in the muscle coat further towards the urethral end of the vas. The distribution of fluorescent and acetylcholinesterase‐positive nerves correlated well with the arrangement of adrenergic and non‐adrenergic terminal regions identified on permanganate fixed sections using the electron microscope. Their distribution was endorsed using 6‐hydroxydopamine to selectively damage adrenergic terminals. Adrenergic nerve terminals were frequently observed in isolation amongst smooth muscle cells while the non‐adrenergic type were almost invariably associated with other axons. The significance of these observations is discussed.
Topographical development of the ganglion cell fiber layer in the chick retina. A whole mount study
Authors: Goldberg Stephen , Coulombre Alfred J. 
Published: December 2004

AbstractThree hundred and forty whole mounts of retinas from domestic fowl aged two days of incubation to several months post‐hatching were examined using a modified pyridine‐silver technique. The first visible ganglion cell axons appeared near the posterior retinal pole between two and three days of incubation. These early axons grew immediately toward the optic stalk and became grouped in fascicles even before reaching it. The fascicles increased in number, diameter and length, became interconnected and became more parallel and orderly with age. The mean fascicle diameter and concentration increased with nearness to the optic fissure. Growth cones were seen only in the most vitread portion of the fiber layer.Two main groups of fascicles, one superficial and one deep, surrounded the head of the fissure by five days of incubation, each group entering the fissure at a different angle. At this time an arcuate pattern of fibers arose near the posterior pole of the retina. Fiber bundles were relatively thin and sparse in the center of this pattern. The distance between the fissure and the center of the pattern increased with age. The arcuate pattern virtually disappeared within several weeks, possibly indicating an abortive formation of a macula and fovea.The fibers at the periphery of the older retinas ran parallel to the iris, encircling but not entering it. These circumferential fibers, which first developed on the temporal side of the retina and later nasally, diverged from a point on the dorsal periphery of the retina. The relative position of this divergence point swung about 90° around the retinal periphery between five and one‐half and eight days of incubation.Probable centrifugal fibers were first seen at 17 days of incubation.
Xenoplastic eye transplantation between chick and quail embryos: Some neuroanatomical and functional aspects
Authors: Heaton Marieta Barrow 
Published: December 2004

AbstractXenoplastic eye exchanges were made between domestic chick and Bobwhite quail embryos, using microsurgical techniques at early stage 11. Donor (quail) eyes were found to be incorporated in 78% of the operations, and it was suggested that an optimal period (late stage 10 ‐ early stage 11, approximately 10.3 somites) exists, during which transplantation of these organs may be maximally successful. The majority of the transplanted eyes appeared normal, and histological examination revealed normally decussating and ingrowing optic nerves which formed normal appearing optic tracts and found terminations within the contralateral tecta. Inspection of donor retinae and the isthmo‐optic nuclei contralateral to the transplant, both known to undergo cellular degeneration in the absence of their appropriate projection fields, showed normal cellular complements and organization in most cases. Functional capacities of the transplanted eyes were assessed by viewing the pupillary light reflex. This test indicated that functional connections were made, at least as far as mesencephalic centers, with the latencies of and threshold intensities for elicitation of the reflex virtually identical in normal and transplanted eyes. The latencies of the reflex virtually identical in normal and transplanted eyes. The latencies of the donor (quail) eyes were considerably shorter than those usually found in these embryos at the age viewed. Some form of host induction of precocial responsiveness is discussed in this connection.
Reduction of the naturally occurring motor neuron loss by enlargement of the periphery
Authors: Hollyday Margaret , Hamburger Viktor 
Published: December 2004

AbstractMotor hyperplasia following the enlargement of the periphery by implantation of a supernumerary leg is not due to “remote control” of proliferation, as shown by motor neuron counts in 6‐day chick embryos. We have tested the alternative hypothesis that we are dealing with reduction of the naturally occurring cell death. In normal development, the lumbar lateral motor column (l.m.c.) undergoes motor neuron degeneration resulting in a cell loss of at least 40%, which occurs between six and one‐half and nine and one‐half days. Following transplantation of supernumerary legs, cases selected for vigorous motility showed a numerical difference between experimental and contralateral (control) sides amounting to +11.0% to +27.5%. The transplants were innervated by varying combinations of thoracic and rostral lumbar nerves. We interpret our data in terms of survival of motor neurons which normally would have failed in a competition at the periphery but which were sustained by the enlarged peripheral fields. Our data do not permit a decision between the two alternatives: competition for synaptic sites or for a trophic agent. The surviving motor neurons are not limited to the rostral segments of the motor column but in most instances distributed along its entire rostro‐caudal extent, implying a redistribution of all l.m.c. axons. The term “hyperplasia” is no longer appropriate for the phenomenon under consideration and should be replaced by the term “hypothanasia.”
An ultrastructural morphometric study of mossy fiber endings in pigeon, rat and man
Authors: Paula‐barbosa M. M. , Sobrinho‐simões M. A. 
Published: December 2004

AbstractMossy fiber endings and their synapses have an increasing morphological complexity along the phylogenetic scale which is specially evident when the evolution from reptiles to birds is considered. Among birds and mammals, only scanty and merely qualitative differences have been noticed in the mossy fiber organization. In the present study, the mossy fiber endings organization within the neuropil of four pigeons, four rats and six men was studied at optic and ultrastructural levels using morphometric methods. No significant differences were found in the fraction of volume of the neuropil and in the number of granule cells per unit volume of granular layer in all the three species. In man, a significant decrease in the volume of mossy fiber endings per unit volume of neuropil, and significant increases in their surface‐to‐volume ratio, in the fraction of their neurolemma occupied by synaptic contacts and in the average length of their synaptic contact zones, were found. The total synaptic area of mossy fiber endings per unit volume of neuropil was larger in man than in other animals in spite of their more reduced volume.These results show that significant differences in mossy fiber organization can be demonstrated when man is compared with a small mammal (the rat) and a bird (the pigeon). It is suggested that differences in the stereological organization of man's terminals might be related to his capacity for making finely graded movements. Moreover, it is suggested that the phylogenetic evolution of the mossy fiber organization has progressed among the higher vertebrates as it did in the rest of the animal scale.
Central projections of the chorda tympani nerve in the mallard, Anas platyrhynchos L
Authors: Dubbeldam Jacob L. , Karten Harvey J. , Menken Steph B. J. 
Published: December 2004

AbstractThe central projections of the chorda tympani nerve in the duck were studied by means of the Fink‐Heimer technique. Following section of the VIIth nerve proximal to the geniculate ganglion terminal projections of the CT are found in the sensory nucleus N VII (sVIId) on the dorsum of the descending trigeminal root, the n. presulcalis anterior solitarii, the n. sulcalis anterior solitarii p. dorsalis and p. ventralis, and the n. ventrolateralis anterior solitarii (Vla). Small quantities of terminal degeneration are also found in the n. intermedius anterior and the lateral substantia gelatinosa of the solitary complex. A number of fibers decussate to terminate contralaterally in corresponding portions of the opposite solitary complex. Comparison with data of the pigeon reveals a limited overlap of projections of the chorda tympani nerve and of the nodose ganglion, respectively, in the dorsal and ventral parts of the n. sulcalis anterior. We suggest that the regions sVIId and Vla alone may convey gustatory information.