This study aimed to better understand the clearance of myelin debris during Wallerian degeneration in the goldfish visual paths. Myelin debris was first examined immunohistochemically in the presence or absence of regenerating axons. From these preliminary experiments it was apparent that the clearance of myelin debris was not affected by regenerating axons and that the debris was removed in a differential pattern along the visual pathway. Specifically, in the distal stump of the nerve as well as in the optic tract, myelin debris had been effectively cleared by one-month postoperative, while in the cranial segment of the nerve debris persisted for at least 6 weeks after injury. The differential pattern of myelin debris in the optic nerve and tract was then analyzed qualitatively and quantitatively using thick and thin plastic sections at various time points during regeneration. The results suggested that highly activated peripheral macrophages were responsible for the effective clearance of myelin in the distal nerve stump. In the optic tract a number of cellular properties, including their unique population of astrocytes may have enhanced the rate of debris clearance. By contrast, in the cranial segment of the nerve persistent debris was found both intracellularly in phagosomes and extracellularly, suggesting that the resident phagocytes were deficient in effecting both phagocytosis and emigration. Deficient phagocytosis may be a result of the production of anti-inflammatory cytokines in this region, while the failure to emigrate is most likely due to the rigid network of astrocytes in the nerve.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.21529 |
| Date | January 1998 |
| Creators | Colavincenzo, Justin. |
| Contributors | Levine, R. L. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001655195, proquestno: MQ50740, Theses scanned by UMI/ProQuest. |
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