Interference of oncogenic N-nitrosourea in intraocular tumor induction by human adenovirus type 12 in rats was examined. Transplacental administration of methylnitrosourea to rat embryo reduced significantly the latent period of the intraocular adenovirus tumor in each animal whereas in groups preadministered with ethylnitrosourea the decrease in the latent period showed marked individual variation. Preadministration of N-nitrosourea caused little change in the morphology and incidence of adenovirus tumors. The histological picture of adenovirus induced intraocular tumors which developed in each group of rats was that of retinoblastoma-like tumor identical to the tumor induced by single virus injection.</p
