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Selective induction of melanomas in gerbils (Meriones unguiculatus) following postnatal administration of N-ethyl-N-nitrosourea.

Following a single ip injection (50 mg/kg) of N-ethyl-N-nitrosourea (ENU) on postnatal day 7 or 20, 9 of 21 gerbils (43%) developed a total of 15 cutaneous melanomas. The mean survival time of tumor-bearing animals was 909 +/- 212 (SD) days. Neoplasms were preferentially located at sites with little hair and with high content of pigment cells (feet, ears, tail, or snout). Histologic studies on newborn gerbils indicated that ENU-induced malignant transformation occurred in differentiated melanocytes rather than in precursor cells of the neural crest.