The pattern of regenerating optic axons following various surgical manipulations in the goldfish brain has been studied using ('3)H proline radioauthography. The results demonstrate that in most cases severed optic axons regenerate preferentially into degenerating axonal pathways. It is therefore suggested that the degenerating axonal debris and the concomitant glial proliferation in a degenerating pathway, in some way, influences the entry of regenerating optic axons into the path. However, in view of the exceptional cases in which regenerating optic fibers either failed to grow into a degenerating pathway, or grew into pathways which apparently did not degenerate, it is further suggested that the influence of the degenerating pathways on the regenerating optic axons is neither 'compelling' nor 'restrictive'. Similarly, although the results also demonstrate that denervated optic terminal zones may influence the choice of pathways by regenerating axons and that the proximity of a pathway to the regenerating optic axons may do so as well, such influences are also neither 'compelling' nor 'restrictive'. Taken together, the data presented here indicate that the guidance of regenerating optic axons is probably influenced by a combination of these factors.

Patterns of proliferation and changes in total cell number in the optic nerve, tract and tectum of goldfish have been examined following optic nerve crush or optic enucleation, using bromodeoxyuridine to label the proliferating cells. In general, an increase in proliferation and total cell number in all parts of the visual system was observed peaking between 7 and 14 days and resolving itself to normal or near normal levels by 32 days postoperative. Enucleation resulted in elevated proliferation values as compared to animals with an optic nerve crush, at least one early timepoint in each part of the visual system, but overall, there is little to suggest that axons are exerting a major effect on the cellular response. Finally, a seasonal effect on the proliferative response of non-neuronal cells and axonal regrowth has been demonstrated. Fish acclimatized under autumn-like conditions showed a faster initiation of the non-neuronal cell response and an enhanced rate of axonal regrowth when compared to fish acclimatized under spring-like conditions. It is believed that photoperiod plays a major role in the seasonal effects observed with temperature playing only a minor one.

No description available.

The role that various myelin membrane proteins play during development and disease processes is not well understood. To better understand their role in vivo we have crossed transgenic mice possessing a single truncated pmp22 gene with mice expressing yellow fluorescent protein in the cytoplasm of their neurons. The resulting double transgenic mice were examined by a combination of confocal microscopy, transmission electron microscopy, and immunohistochemistry to determine if pmp22 insufficiency alters the structural integrity of myelin, glial cells, axons, or the subcellular milieu of these various components. Axons from mice with pmp22 insufficiency developed sprouts and debris localized to nodes with no signs of degeneration of a Wallerian type. Ultrastructurally, the nodes accumulated tubovesicular structures as well as disrupted cytoskeleton that did not appear to alter axon transport. Together, these results suggest that pmp22 insufficiency leads to a non-lethal axonopathy that is restricted to nodes. / Department of Physiology and Health Science

Access to abstract permanently restricted to Ball State community only. / Access to thesis permanently restricted to Ball State community only. / Department of Biology

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.

Thesis (Ph.D.). / Written for the Dept. of Neurology and Neurosurgery. Title from title page of PDF (viewed 2008/05/12). Includes bibliographical references.

Thesis (Ph.D.). / Written for the Dept. of Anatomy and Cell Biology. Title from title page of PDF (viewed 2008/05/12). Includes bibliographical references.

Thesis (M.Sc.). / Written for the Dept. of Neurology and Neurosurgery. Title from title page of PDF (viewed 2008/05/14). Includes bibliographical references.