Biological activity in the repopulating rat spermatocyte after the withdrawal of gossypol treatment: I. The activity for DNA synthesis.

Mature male rats were treated with gossypol for various lengths of time after which the treatment was stopped to allow the arrested spermatogonia to revive. Fifteen days after withdrawal of the drug treatment, the arrested spermatogonia entered into the meiotic division and then reached the pachytene stage. The meiotic cells derived from the arrested spermatogonia were the first generation of the differentiated germ cells after long-term gossypol treatment. Centrifugal elutriation technique was used to isolate the repopulating pachytene spermatocytes (RPS) or the control pachytene spermatocytes (CPS) from the rat testis with or without receiving gossypol pretreatment. In vitro culture condition for RPS and CPS was established for the synthesis of DNA by the measurement of 3H-thymidine incorporation. The activity for DNA synthesis in RPS was studied and compared to that of the CPS. It was concluded that after gossypol treatment for various times, the incorporation of 3H-thymidine into the cellular thymidine pool of RPS was not affected. However, the activity for DNA synthesis in RPS was significantly lower than that in the CPS. The synthetic activity for DNA was reduced by 14%, 26%, 42%, 40%, and 40% in the RPS for the gossypol pretreatment of 3, 4, 6, 7, and 8 weeks, respectively.