X-irradiation-induced changes in the progression of type B spermatogonia and preleptotene spermatocytes

In response to induced DNA damage, proliferating cells arrest in their cell cycle or go into apoptosis. Ionizing radiation is known to induce degenera tion of mammalian male germ cells. The effects on cell-cycle progression, h owever, have not been thoroughly studied due to lack of methods for identif ying effects on a particular cell-cycle phase of a specific germ cell type. In this study, we have utilized the technique for isolation of defined seg ments of seminiferous tubules to examine the cell-cycle progression of irra diated rat mitotic (type B spermatogonia) and meiotic (preleptotene spermat ocytes) G1/S cells. Cells irradiated as type B spermatogonia in mitotic S p hase showed a small delay in progression through meiosis. Thus, it seems th at transient arrest in the progression can occur in the otherwise strictly regulated progression of germ cells in the seminiferous epithelium. Contrar y to the arrest observed in type B spermatogonia and in previous studies on somatic cells, X-irradiation did not result in a G1 delay in meiotic cells . This lack of arrest occurred despite the presence of unrepaired DNA damag e that was measured when the cells had progressed through the two meiotic d ivisions. (C) 2001 Wiley-Liss, Inc.