Comparative aspects of the effects of radiation during oogenesis

Primordial germ cells, which are relatively resistant to radiation administered prior or during migration, become sensitive during sex differentiation of the gonad. Sensitivity increases to a maximum during the peak “wave” of mitosis in oogonia, and especially during the final premeiotic division. The oocyte subsequently becomes increasingly resistant to radiation as it progresses from leptotene to pachytene, after which sensitivity increases with the onset of the period of arrested development (diplotene or dictyate stage).