Aplasia of the Optic Nerve in Microphthalmic Offspring of Prenatally X-irradiated Rats

A considerable number of postnatally-viable microphthalmic offspring with optic nerves completely absent were obtained by X-irradiation at a dose of 100 R in pregnant rats on gestational day 10.5. Thirteen of 15 mi-crophthalmic eyes examined displayed histological features characteristic of aplasia of the optic nerve: complete absence of optic papilla, nerve fiber layer and retinal blood vessels, and great reduction in the number of ganglion cells. The remaining 2 eyes showed the histological features of hypoplasia of the optic nerve. The present experimental system may afford suitable materials for postnatal patho-genetic studies and also for various physiological and behavioral studies of aplasia of the optic nerve.