Stage-specific sensitivity of spermatogonia to different chemotherapeutic drugs.

The sensitivity of cells at different stages of spermatogenesis in the mouse to various chemotherapeutic drugs will be reviewed in order to compare the actions of related drugs. The rapidly dividing differentiated spermatogonia are most sensitive to all drugs. Cells at later stages, which do not synthesize DNA but still undergo meiotic division, are most resistant. Slowly proliferating spermatogonial stem cells are of intermediate sensitivity. In general, these stem cells are most sensitive to intercalating antibiotics, less sensitive to alkylating agents, and most resistant to antimetabolites, although there are differences between agents within each group. The concept of differential sensitivity of mouse spermatogonia can be used to explain varying durations of sterility in patients treated with different chemotherapeutic drugs, but the results obtained with specific drugs in the mouse may be extrapolated directly to man.