Induction and survival of micronuclei in rat spermatids. Comparison of two meiotic micronucleus techniques using cyclophosphamide.

The induction and survival of micronuclei (MN) in rat spermatids was studied by two different methods, the dissection method (DM) and the suspension method (SM). It was observed that MN are induced by cyclophosphamide in the S phase of meiosis, in preleptotene spermatocytes, and in an earlier cell stage, the type B spermatogonia. Both techniques showed that MN survive in spermatids at least 5 days. Advantages of the DM include the use of a DNA-specific fluorochrome for staining of MN, higher MN frequencies observed, and the possibility to gain detailed information of the kinetics of induction of MN. In the SM, slide preparation is simpler than in the DM, and several samples can be prepared simultaneously but the scoring of slides is time consuming. Improvements of the sampling system of the DM are suggested. For evaluation of clastogenic action of chemicals on male germ cells both techniques provide a simple and rapid approach.