Wallerian degeneration in the optic nerve of the wabbler-lethal (wl/wl) mouse

Optic nerve pathology was studied in C57BL/6J wabbler-lethal (wl/wl) and control (+/+) mice at postnatal age of 4 weeks (P28). Qualitative light and ultrastructural pathology in wl/wl animals conformed to the criteria of primary axonal (Wallerian) degeneration. Most optic nerve axons in mutant animals appeared normal, as did oligodendroglia, the degree of myelination, the integrity and maturity of vascular elements, astroglia, and most myelin. Still, degenerating axons surrounded by somewhat normal myelin and axons with thickened myelin sheaths were prevalent in wl/wl mice. Dysmyelination or hypomyelination was not evident. At P28, pathology appeared more prominent in large diameter fibers. In the optic nerve of wl/wl mice, axonal degeneration preceded myelin disruption, adding this nerve to other previously reported systems undergoing Wallerian degeneration in this mutant.