Abstract

An experiment is described which tests for visible and invisible mutants in mice treated with four different doses each of the contraceptives Gynanovlar and Lyndiol. The results show that there is no reason to suppose that either substance has an appreciable mutagenic effect, expressed as an increase of antenatal and postnatal lethals or visibles. The substrain CBA/CagCam, used throughout, has an incidence of 0.27% of singly occurring abnormalities, mainly of the appendicular skeleton, which distinguishes it from the parent CBA strain and its axial variation described by Gruneberg (1963).