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Quantitative evidence for continuing axonal pathology after optic nerve stretch‐injury
Author(s) -
Domleo A.,
McColl G.,
Graham D. I.,
Maxwell W.
Publication year - 2002
Publication title -
neuropathology and applied neurobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.538
H-Index - 95
eISSN - 1365-2990
pISSN - 0305-1846
DOI - 10.1046/j.1365-2990.2002.39286_35.x
Subject(s) - axotomy , neurofilament , optic nerve , myelin , anatomy , guinea pig , medicine , pathology , central nervous system , immunohistochemistry
Stretch‐injury to the optic nerve of the guinea‐pig results in cytoskeletal pathology. We tested the hypothesis that post‐traumatic changes may continue up to 1 week after injury. Material and methods: Six animals were injured under controlled conditions. Under terminal anaesthesia, three controls and three animals were killed at 24 h or 1 week. Unbiased stereological analysis of the axonal cytoskeleton was undertaken. Results: At 4 h, 20% of nerve fibres are injured (Jafari et al . J Neurotrauma 1998; 15 : 955). In the present study, no evidence for a change in the proportion of injured nerve fibres at longer survivals was obtained. At 24 h, three types of injured fibre occur: (i) some are compacted as at 4 h; (ii) some, termed ‘degenerating’, show loss/increased spacing between neurofilaments and microtubules ( P = 0.005); and (iii) in some, empty myelin figures occur. At 7 days, both degenerating fibres and empty myelin figures are increased ( P = 0.032). Conclusions: These results demonstrate that injured nerve fibres undergo secondary axotomy between 4 and 24 h and there are increased numbers of degenerating fibres at 7 days. However, not all injured fibres undergo axotomy between 4 and 24 h, because, at 7 days fibres undergoing axotomy are present.