bluuebunny/crossref_metadata_2025_split huggingface dataset:
The corticopontine projection from the visual cortex of the cat: An autoradiographic investigation
Authors: Fries W. , Albus K. 
Published: May 2005

AbstractThe cortico‐pontine projections from striate (kV), parastriate (paV) and peristriate (peV) areas of the neocortex of the cat have been investigated using an anterograde axoplasmic tracing method. Injections of tritiated amino‐acids have been made at cortical locations whose visual field positions were determined in some experiments electrophysiologically. It has been found that the density of the projection varies depending on the location of the injections within each area. In addition differences in the density of the pontine projection have been found between the three visual areas. Both in kV and paV no pontine projection was detected from cortex representing the area centralis. An increase of the projection from cortex with paracentral to peripheral visual field representations was found in kV for the lower hemifield (the upper hemifield has not been investigated) and in paV for the entire hemifield. In addition it has been found that a denser projection arises from the representation of the lower visual field in paV and peV than from the representation of the lower visual field in paV and peV than from the representation of the upper visual field.The cortico‐pontine projection has been found to increase from kV (V1) through paV (V2) to peV. Since the injections in peV were not restricted to the region of the third visual representation (V3), they do not allow a definite conclusion to what extent the increased projection from peV can be attributed to V3.The terminations from the three visual areas are largely restricted to the rostral third of the pontine basilar gray. The labelled terminals were not restricted to any one of the nuclei of this region which have been delimited by Brodal and Jansen ('46). The terminals formed patches of variable size near the ventral aspect of the cerebral peduncles. A clear retinotopic distribution of these patches could not be demonstrated.
Monoamine fluorescence and electron microscopic studies on small intensely fluorescent (granule‐containing) cells in human sympathetic ganglia
Authors: Chiba Tanemichi 
Published: May 2005

AbstractIn the present study, surgically removed adult human sympathetic ganglia were explored for the presence of small intensely fluorescent (SIF) cells using a combined monoamine fluorescence and electron microscopic method (Chiba et al., '76b). It was confirmed that SIF or granule‐containing (GC) cells exist as a persisting constituent of the ganglia. The population of SIF cells in human sympathetic ganglia was found to be much smaller than that of the rat and the guinea pig. Most SIF cells were found as small clusters in the connective tissue stroma in close relationship with blood vessels. GC cells were characterized by large polymorphic granular vesicles (100–300 nm in diameter) in their cytoplasm. Most GC cells were innervated by cholinergic axons which most probably originated from preganglionic sympathetic neurons. No efferent synapses were found from GC cells as far as they were examined.Axon varicosities containing small dense granular vesicles (50 nm in diameter) may correspond to varicose fluorescent network of axons among principal ganglionic neurons. The functional significance of SIF or GC cells in human sympathetic ganglia was discussed in the light of the present observations.
The origin of brainstem‐spinal pathways in the north american opossum (didelphis virginiana). Studies using the horseradish peroxidase method
Authors: Crutcher Keith A. , Humbertson Albert O. , Martin George F. 
Published: May 2005

AbstractBrainstem neurons which project to lumbar, thoracic and cervical spinal levels have been identified in the North American opossum by the horseradish peroxidase (HRP) technique. Neurons which relay to all of the levels studied are located within the medullary and pontine reticular formation as well as within the nucleus cuneatus, the nucleus of the tractus solitarius, the lateral reticular nucleus, the medullary and caudal pontine raphe nuclei, the lateral, medial and inferior vestibular nuclei, the nucleus “F,” the nucleus coeruleus, and the nucleus coeruleus, para α, the red nucleus, and the interstitial nucleus of Cajal. The lateral vestibulospinal and rubrospinal systems are topographically organized, although neurons projecting to different cord levels show considerable intermingling. Our material also provides evidence that raphe‐spinal and reticulospinal connections are organized to some degree. Neurons which backfill after cervical and thoracic placements, but not after lumbar injections, are distributed within the caudal spinal trigeminal nucleus, the nucleus intercalatus, the dorsal vagal nucleus, the cuneiform area of Castaldi, the fields of Forel, and the nucleus of Darkschewitsch. Reactive neurons are present within the lateral, dorsal and posterior hypothalamic areas as well as within the periventricular and paraventricular nuclei after thoracic placements and within the superior colliculus after injections within the cervical cord. Additionally, neurons are reactive in the nucleus ambiguus, the interpolar division of the spinal trigeminal nucleus and the rostral division of the oculomotor nucleus (Oswaldo‐Cruz and Rocha‐Miranda, '68) after HRP placements into the third and fourth cervical segments.
Retinal abnormalities in the Siamese cat
Authors: Stone J. , Rowe M. H. , Campion J. E. 
Published: May 2005

AbstractGanglion cell density maps of the retinas of Siamese cats show the same major features of ganglion cell distribution as are found in normally pigmented cats, in particular the area centralis and visual streak. In the retinas of the seven Siamese cats investigated, however, the area centralis was “underdeveloped” when compared with the normally pigmented cat. The beak ganglion cell density was lower and the ganglion cells usually larger than at the area centralis of the normally pigmented cat, and the characteristic blood vessel pattern around the area centralis was less developed. One animal showed a marked blood vessel abnormality, a vessel crossing the area centralis in each retina. In another animal, the distribution of ganglion cells appeared abnormal throughout the retina. Medium‐sized, possibly X‐type ganglion cells were lacking from all retinal areas, overall cell numbers were low and the distribution of ganglion cells showed a prominent visual streak.
Fine structure of reactive cells in injured nervous tissue labeled with 3H‐thymidine injected before injury
Authors: Adrian Erle K. , Williams M. G. , George F. C. 
Published: May 2005

AbstractTo examine the fine structure of blood mononuclear cells in injured nervous tissue, mice were given repeated injections of 3H‐thymidine with the last injection at least 16 hours before injury. Under ether anesthesia the animals either were given a stab wound to the spinal cord or had their left hypoglossal nerve transected. The animals were killed at 2, 4, 8, or 16 days after injury. Tissue sections containing the spinal cord wound or both hypoglossal nuclei were prepared for electron microscopic radioautography, and all labeled cells were photographed. About half the labeled cells in the injured hypoglossal nerves had nuclei with dark staining peripheral heterochromatin, dark cytoplasm with long cisternae of granular endoplasmic reticulum, and other ultrastructural features characteristic of the cells usually identified as microglia. The remaining labeled cells in the injured spinal cords were macrophages, fibroblasts, cells with pale nuclei, some of which contained cytoplasmic filaments, and vascular cells. Since uninjured nervous tissue has extremely few labeled cells and since 3H‐thymidine should be available for only a short time following injection, most of the labeled cells in this experiment should be derived from blood mononuclear cells. However, the possibility is discussed that some or all of the labeled cells proliferating in response to the injury and labeled through reutilization of labeled DNA precursor material.
A stereotaxic atlas of the brain of the three‐day‐old domestic chick
Authors: Youngren Orlan M. , Phillips Richard E. 
Published: May 2005

AbstractPreparation of a stereotaxic atlas of the brain of the 3‐day‐old domestic chick was prompted by the widespread use of chicks in behavioral and pharmacological research.The atlas is comprised of 26 frontal plates extending from the frontal pole to the level of the hypoglossal nucleus, and one sagittal plate at lateral 0.4 mm. Marking lesions were used to ascertain coordinates, the brains were embedded in albumin and sections cut at 36 mμ. The brain sections were stained with cresyl violet for nuclei and with hematoxylin for fibers. Unstained brain sections were used as a guide in drawing the plates to correct for shrinkage and distortion.The use of the atlas for research purposes for one year, plus test lesions targeted for specific brain structures, indicates the atlas is accurate to within 0.5 mm.
Regional differences in pigeon optic tract, chiasm, and retino‐receptive layers of optic tectum
Authors: Duff Thomas A. , Scott Grayson , Mai Regina 
Published: May 2005

AbstractElectron‐microscopic examination of the pigeon optic chiasm, tract, stratum opticum, and retino‐receptive layers of the optic tectum revealed regional differences at each level. Axonal size in the fiber pathways paralleled that previously reported for pigeon optic nerve, with mean diameter values of 0.96 μm for optic chiasm and 1.06 μm for optic tract. The dorsolateral aspects of these pathways contained a heterogeneous population of fibers (mean diameter ⋍ 1.44 μm) similar to that found in the nasal portion of optic nerve, while the ventromedial regions were occupied by a more homogeneous population of smaller fibers (mean diameter ⋍ 0.82 μm) resembling those observed in the temporal portion of the nerve.The retino‐receptive layers of anteroventral optic tectum (avT) differed ultrastructurally from those of posterodorsal tectum (pdT) with respect to the thickness of horizontal dendrites in layers 2–3, the size of optic terminals in layers 2–7, and the number of synaptic contacts per terminal. These findings point towards a regional variation in the processing of visual information throughout the retino‐tectal system and suggest that neurons in avT vs. pdT should show differences in the way they modify the neurophysiological characteristics of their respective optic inputs.
Freeze fracture study on three types of synapses in the Xenopus spinal cord
Authors: Watanabe Hiroshi , Yamamoto Toshi Yuki 
Published: May 2005

AbstractThree types of synapses (S‐, F‐ and C‐types) were identified in the thin‐sectioned Xenopus spinal cord and their structure was analyzed with the freeze‐fracturing technique.All three types of synapses showed similar specializations of the presynaptic membrane. This finding suggests that the three types of synapses may release their transmitters by a similar mechanism. By contrast, the three types of synapses revealed different specializations of the postsynaptic membrane. The E‐face of the S‐type postsynaptic membrane was characterized by a dense aggregate of large intramembrane particles, 12 to 15 nm in diameter. An aggregate of small particles, 8 to 9 nm, was evident on the E‐face of the postsynaptic membrane of the F‐type synapse. In the C‐type synapse, there was a striking aggregate of intramembrane particles, 10 to 14 nm in diameter, on the P‐face of the postsynaptic membrane. These characteristics features in the distribution of particles in the three types of postsynaptic membranes may reflect differences in the type of transmitter released or transmitter action on the postsynaptic neuron.The overall size of the area of aggregated particles on the P‐face of the C‐type postsynaptic membrane was coextensive with the underlying subsurface cistern (SSC) which showed partial occulsion of the lumen. This fact supports the view that the SSC is closely related to the C‐type synaptic action which might be distinct from the other synaptic types.
3H‐Thymidine autoradiadiographic analysis of telencephalic histogenesis in the chick embryo: II. Dynamics of neuronal migration, displacement, and aggregation
Authors: Tsai Huei Mei , Garber Beatrice B. , Larramendi Luis M. H. 
Published: May 2005

AbstractThe movements of cells from their sites of origin in the proliferative neuroepithelium to their final positions in the chick telencephalon were traced by autoradiographic analysis of 3H‐thymidine‐labeled brains. A series of chick embryos were labeled on successive days of development between days 5 and 9 and fixed for autoradiography between days 6 and 10. Isochrone maps visualizing neuronal positions on each day of development between days 6 and 10 provided direct information concerning cell migrations, displacements, and aggregations leading to compartmentalization of the telencephalic wall and the generation of the “outside‐in” pattern of histogenesis characteristic of the avian telencephalon. The topological divisions of the telencephalic wall appear to result from two factors: (1) the specification of neuronal precursors within the neuroepithelium and (2) the intrinsic associative and migratory properties of postmitotic neuronal populations expressed within the mantle layers. There was no evidence that glial cell barriers mediated the initial compartmentalization of neuronal populations.
An intracellular electrophysiological study of the ontogeny of functional synapses in the rabbit retina. I. Receptors, horizontal, and bipolar cells
Authors: Dacheux Ramon F. , Miller Robert F. 
Published: May 2005

AbstractAn isolated perfused retina‐eyecup of the rabbit neonate was used to study the functional maturation of synaptic interactions in the outer plexiform layer. Intracellular recordings from receptors, horizontal cells, hyperpolarizing and depolarizing bipolar cells were obtained in the adult and at different stages of maturation. Three types of horizontal cells could be distinguished based on the relative amount of rod and cone input, response wave form, receptive field diameter, and amplitude‐intensity relationships. Two of the horizontal cell types were encountered with sufficient frequency such that maturation of these response characteristics could be followed over the developmental period of this study (8 days–adult). The growth rate of the amplitude‐intensity relationships was different for the two commonly encountered types of horizontal cells; the small diameter receptive field type achieved an adultlike amplitude‐intensity range at an earlier age than the large field type. Immature bipolar cell responses were initially monophasic potentials with transient‐sustained components appearing at a later stage. Center surround antagonism of bipolar cells developed after centermediated responses were first observed. This suggests some secondary modifications during synaptogenesis are responsible for the late maturation of center surround antagonism. The morphological appearance of synaptic contacts during different stages of synaptogenesis is discussed in reference to the different phases of functional, synaptic interactions of this study. It appears that some synapses in the vertebrate retina are functional at a time when synaptic structure is incomplete, based on ultrastructural observation. Maturation of receptive field diameter and amplitude‐intensity function is discussed in relationship to possible presynaptic and postsynaptic mechanisms which may influence this growth.
The development of the oculomotor nuclear complex in the Japanese quail embryo
Authors: Heaton Marieta Barrow 
Published: May 2005

AbstractThe development of the oculomotor nuclear complex was studied in the Japanese quail. In hatchlings, this complex was found to consist of four subnuclei: The accessory, the dorsolateral, the dorsomedial, and the ventromedial. An arciform subnucleus or central subnucleus was not found in this species. All subnuclei were made up of homogeneous cell populations. The oculomotor primordia can first be recognized at day 3 of incubation, and a clear subdivision within this primordia is apparent on day 5 (total incubation period = 17 days). At this time the accessory subnucleus can be discerned. By day 6, a horizontally oriented dorsal cell mass, the anlagen of the dorsolateral and dorsomedial subnuclei, is seen, as is a vertically oriented ventral cell mass, the anlagen of the ventromedial subnucleus. The boundaries between the subnuclei are not yet distinct at this age, however. By day 7 of incubation, all four subnuclei can be detected as separate entities. Migrating cells, apparently moving primarily between the ventromedial subnuclei, are first seen on day 5, at which time the oculomotor commissure begins to appear. Migratory traffic is extensive during days the 6 and 7 of incubation, with wide bands of migrating cells typically seen, spanning the entire dorsal‐ventral extent of the oculomotor complex. These cells do not appear to be associated exclusively with the ventromedial subnuclei. In many instances, migratory cells appear to be affiliated with the dorsomedial cell group. By day 10 of incubation, migration has ceased and the oculomotor complex has attained its definitive configuration. These observations are discussed with comparative reference to earlier studies of chick and duck embryos and hatchlings.
The ascending projection of the nucleus of the lateral descending trigeminal tract: A nucleus in the infrared system of the rattlesnake, Crotalus viridis
Authors: Stanford L. R. , Schroeder Dolores M. , Hartline Peter H. 
Published: May 2005

AbstractThe efferent projections of the nucleus of the lateral descending trigeminal tract (LTTD) in the rattlesnake (Crotalus viridis) were studied by anterograde tracing techniques. The LTTD, a brainstem trigeminal nucleus, is the sole projection site of the infrared‐sensitive trigeminal fibers that innervate the pit organs in these snakes. The efferent fibers exit from the ventromedial edge of the LTTD and course medially and caudally toward the central grey area of the medulla. Upon reaching the central region of the medulla these fibers turn and move laterally and rostrally, eventually forming a tract on the ventrolateral surface of the brainstem. Embedded in this tract and slightly overlapping the LTTD in the rostrocaudal axis, is a population of large (20–45 μm) multipolar neurons that forms the nucleus reticularis caloris. Heavy terminal and preterminal degeneration in this area indicates that many of the efferent fibers of the LTTD terminate in this nucleus. A small bundle of degenerating fibers turn dorsally from the ventrolateral tract and ascend to terminate in a nucleus associated with the cerebellum, the lateral tegmental nucleus. No projection was found to any other nuclei or areas in the brain.This study demonstrates that the infrared‐sensitive snakes, along with developing peripheral specializations (the pit organs), have developed specialized nuclei to handle this additional sensory information. The direct projection from the LTTD to the nucleus reticularis caloris provides a pathway linking the infrared sensitive neurons of the LTTD with neurons of the same modality in the optic tectum. The second LTTD projection, to the lateral tegmental nucleus, suggests a connection between the infrared system and the cerebellum in these animals.
Synaptic termination of thalamic and callosal afferents in cingulate cortex of the rat
Authors: Vogt Brent A. , Rosene Douglas L. , Peters Alan 
Published: May 2005

AbstractThe distribution of degenerating thalamic and callosal afferents to cingulate cortex in the rat is analyzed. Both light microscopic silver impregnation and quantitative electron microscopic techniques demonstrate differences in the form, number, and laminar distribution of these two afferents in anterior and posterior cingulate cortices.Afferents from the mediodorsal thalamic nucleus terminate in area 24. Most terminals are in layer IIIb, fewer in layer Ia–b, and least in layers V and VI. In contrast, callosal afferents terminate mainly in layers Ib–c, II, IIIa, V, and VI. Thus, thalamic and callosal afferents terminate in a complementary pattern except in layers Ib and IIIb where they overlap. Quantitative analysis of degenerating axon terminals in area 24 indicates that there may be as many as seven times more callosal than mediodorsal thalamic terminals in this cortex.Projections of the anterior thalamic nuclei terminate in areas 29b and 29c, primarily in layer Ia, with fewer in layers Ib–IV and least in layers V and VI. Callosal afferents end mainly in layers V and VI and less densely in layers I–IV, which results in some overlap of thalamic and callosal afferents in layers Ic, IV, and V. In addition, patterns of termination of callosal afferents in posterior cingulate cortex change at borders between previously defined cytoarchitectural areas.Anterior thalamic terminals in area 29c differ from other thalamocortical afferents described previously in that they form two types of terminals. One is large (2–4 μm in diameter) and occurs mainly in layer Ia, whereas the second type is smaller and is present in layers Ib–V. Both types of terminals form asymmetric synapses mainly with dendritic spines.
Afferent connections of the rostral medulla of the cat: A neural substrate for midbrain‐medullary interactions in the modulation of pain
Authors: Abols I. A. , Basbaum A. I. 
Published: May 2005

AbstractIn order to study the organization of the rostral medulla of the cat and its contribution to pain control mechanisms, we have examined the afferent connections of the midline nucleus raphe magnus (NRM), the laterally located nucleus reticularis magnocellularis (Rmc), and the nucleus reticularis gigantocellularis (Rgc) located dorsal to Rmc. Iontophoretic injections of HRP were made into the three regions; the distribution of retrogradely labeled neurons in brainstem and spinal cord was then mapped. While significant differences characterize the source of afferents to Rgc and NRM/Rmc, there is little to distinguish that between NRM and Rmc.The predominant spinal projection is to Rgc; fewer labeled neurons were recorded after injections into Rmc. In contrast, no significant direct spinal projection to NRM was found. All three regions receive input from widespread areas within the medullary and pontine reticular formation. The most pronounced differences in the distribution of retrogradely labeled neurons were found in the midbrain. The major projection to both NRM and Rmc derives from the periaqueductal gray (PAG) and from the adjacent nucleus cuneiformis. Labeled cells are concentrated in the dorsal and lateral PAG; few are found in the ventrolateral PAG. In contrast, Rgc receives few afferents from the PAG; however, after Rgc injections, many cells were recorded in the deep layers of the contralateral tectum. None of the injection sites produced significant labeling of the catecholamine‐rich dorsolateral pontine tegmentum or of the nucleus raphe dorsalis.The demonstration of significant PAG projections to NRM/Rmc provides anatomical evidence for the hypothesis that opiate and stimulation‐produced analgesia involves connections from PAG to neurons of NRM and Rmc which, in turn, inhibit spinal nociceptors.