Morphological study of retrograde degeneration followed by optic nerve transection in adult cats
Wakakura, M.
Nippon Ganka Gakkai Zasshi 83(12): 2255-2270
1979
ISSN/ISBN: 0029-0203 PMID: 539519 Document Number: 143088
An optic nerve transection without vascular damage was performed via soft palate approach in 7 adult cats. The transection was performed 6 mm centrally behind the eyeball. A unilateral transection was made. Right after the transection, electroretinography and fluorescein angiography were performed to confirm that there was no vascular damage. The distal (retinal) portion of the transectomized optic nerve was viewed by light microscopy and EM 1, 2, 4 and 12 wk after the transection and compared with 3 normal controls. Reduction in the number of ganglion cells was seen 4 wk after the transection. Reduction was more prominent 12 wk after the transection by light-microscopy. Even 1 wk after the transection, degenerative changes were seen in ganglion cells and axons of nerve fiber layer with EM. A few ganglion cells were necrobiotic. These changes became increasingly severe during the next 11 wk. No evidence of trans-synaptic change was seen even after 12 wk. A marked degeneration of myelinated fibers of the optic nerve just adjacent to the eye ball was not seen until 2 wk after the transection. The degeneration advanced more severely after the 2 wk. The degeneration of non-myelinated fiber at the optic nerve head was always milder when compared with the changes at the retina and the retrobulbar myelinated fiber. The degeneration of the optic nerve head was completed 12 wk after the transection. These changes were not observed in the controls. There apparently were 2 processes of developing degeneration after the transection of the optic nerve; (1) orthograde fiber degeneration originating from the ganglion cells and retrograde fiber degeneration originating from the lesion transected.