Ultrastructural appearances of preneoplastic liver nodules induced through sequential treatment in rats.

The ultrastructural appearances of preneoplastic liver nodules induced in male Wistar rats through sequential treatment with diethylnitrosamine (DENA) and 2-acetylaminofluorene (2-AAF) followed by partial hepatectomy were investigated. Although separately non-specific, the lesions reported represented altogether a fairly characteristic pattern consistent with previous observations in tumors and in preneoplastic nodules induced by long-term treatment with single carcinogens. Such data support the view that sequential treatment followed by partial hepatectomy is a reliable method to study early phenotypic changes in hepatocarcinogenesis. Such treatment is also advisable because it requires only a short period of latency in comparison to other in vivo screening tests of potential carcinogens.