Results here showed that exposure to the Low concentration of PM (the active metabolite of CYP), had less of an effect on germ cell numbers than exposure to Low CIS or DOX (1.5 fold compared to 40- and 50-fold respectively), perhaps a surprising result given that the clinical literature indicates that treatment with alkylating agents in general, and cyclophosphamide in particular, has the strongest association with fertility problems in males34,35. Here, PPIG is linked to in situ carcinoma.