Induction of Melanotic Tumours in the White ('Partial Albino') Syrian Hamster

DELLA PORTA et al. 1 first reported the induction of melanotic tumours in the skin of Syrian golden (agouti) hamsters after topical applications of 7,12-dimethylbenz( a )anthracene (DMBA). This finding was afterwards confirmed by these and other investigators 2–5 . Ghadially and Barker 5 have postulated that the melanotic lesions arise from dermally situated perifollicular networks of melanocytes intimately associated with certain hair follicles. They suggest that the proximity of dermal melanocytes to sebaceous glands of hair follicles renders them especially vulnerable to the action of carcinogens topically applied to the skin. Recently, Illman and Ghadially 6 have reported the induction of melanotic tumours in the general body skin of white (‘partial albino’) Syrian hamsters during repeated topical applications (22 weekly treatments) of 2 per cent DMBA in acetone. It is noteworthy that white hamsters characteristically possess a white hair coat, and grossly detectable pigmentation is restricted to the skin of the ears, perineum and genitals; a darkening of eye colour may occur with advancing age 7,8 . Whiteness of hair coat is a genetically determined trait inherited as a simple Mendelian recessive 7,8 . The purpose of this communication is to report observations made in our laboratory on the occurrence of melanotic lesions in white hamsters treated with DMBA.