Increase in type A virus particles induced in BALB/c mouse epidermis during chemical carcinogenesis.

Electron microscopic observations of normal BALB/c mouse epidermis revealed the presence of isolated intracisternal A particles. Hyperplasia, papilloma and carcinoma formation induced by topical application of the carcinogenic polycyclic hydrocarbons benz(a)pyrene (B(a)P) and 3-methylcholanthrene (MC) is accompanied by an increase in the mumber of A particles. Topical application of a non-carcinogenic irritant alpha-pinene (alpha P) failed to provide comparable changes. Examination of the nuclei indicated occasional electron dense granules in the nucleoplasm which became more common throughout the progression of carcinogenesis.