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Biomedical subjects

C K Henkel

Publications and source records attributed to C K Henkel.

40 records · Page 3Linked to original sources
PubMed1976

Cerebello-olivary fibers: their origin, course and distribution in the North American opossum.

Although degeneration techniques suggest that cerebello-olivary fibers are limited in their origin and distribution, horseradish peroxidase and autoradiographic experiments make it clear that they arise within all cerebellar nuclei and project to most, if not all, areas of the contralateral inferior olive. Autoradiographic preparations show that cerebello-olivary fibers are highly ordered and suggest that the dentate nucleus projects primarily to the principal olive, the interpositus anterior relays particularly heavy to the dorsal accessory nucleus and the interpositus posterior distributes extensively to the medial accessory complex. Evidence for a small projection from the fastigial nucleus to the caudal medial accessory nucleus is also available. However, it appears clear that neither the dentate nor the interpositus nuclei project to just one subdivision of the olive. For example, although dentate fibers end extensively within the principal nucleus some of them also distribute to portions of the medial accessory nucleus and perhaps the dorsal accessory nucleus as well. The medial accessory olive is particularly complex and at rostral levels receives input from both interposed and dentate nuclei, whereas more caudally it receives a projection from the fastigial nucleus. Olivary fibers from both the interposed and dentate nuclei traverse the brachium conjunctivum descendens and distribute primarily to the rostral 2/3 to 3/4 of the olive, whereas those from fastigial neurons take a different route and end more caudally. Experiments utilizing horseradish peroxidase as a retrograde tracer suggest that cerebello-olivary fibers from both the interpositus anterior and dentate nuclei take origin from a population of generally small neurons.

Afferent Pathways↗
PubMed1975

Cortical and brain stem projections to the spinal cord of the American opossum, Didelphis marsupialis virginiana.

The present report describes the results of experiments designed to study supraspinal systems in the American opossum by several techniques. The data indicate that although spinal fibers from the opossum motor-sensory cortex are small and limited in their distribution, those from the brain stem are comparable in their origin, course, caudal extent and distribution to those described for placental mammals. Such results support the use of the opossum as an experimental animal for nervous system research; but, furthermore, suggest that its marsupial embryology makes it an ideal model for experiments designed to elucidate the ontogeny of the nervous system.

Animals↗
PubMed1975

Corticobulbar fibres in the North American opossum (Didelphis marsupialis virginiana) with notes on the Tasmanian brust-tailed possum (Trichosurus vulpecula) and other marsupials.

Corticobulbar projections have been studied in the American opossum by both degeneration and autoradiographic methods and, for the most part, the results confirm our earlier observations (Martin & West, 1967; Martin, 1968). However, we have obtained evidence for certain connexions not previously described and have delineated the origin(s) of several connexions more precisely by paying particular attention to the degeneration present at thalamic levels in all cases and by the use of autoradiography. When our results are collated and correlated with new somatosensory cortical maps arrived at by microelectrode techniques (Pubols et al. 1975), it is obvious that corticolbulbar connexions in the North American opossum are remarkably similar to those in the monkey and differ mainly in quantity, relative origins and distribution and in the fact that some of them arise from spatially co-extensive motor-sensory areas (Lende, 1963a, b). In the light of our findings on the American opossum we have examined a large collection of brush-tailed possum material (as well as some from the potoroo and Tasmanian native cat) and have been able to extend our previous findings (Martin et al. 1971; Martin & Megirian, 1972) to a more precise evaluation of the origin of projections from the limb, face motor-sensory cortex. Differences between these representatives of the marsupial radiation, as well as features which are common to all, are described.

Animals↗