Meiotic prophase in female mice

Abstract

IN a preliminary study of chiasmata in female mice the meiotic prophase was observed in sixty-two females from a variety of strains, mostly outbred. It was found that in all strains the oogonial nuclei in newly born females are without exception in the resting stage probably following the last mitotic division. At about 12 hr. of age the first part of meiotic prophase is appearing and at the age of 60-72 hr. it is completely over. Later the ovary contains oocyte nuclei which are in the 'dictyotene' stage. In this stage they remain until sexual maturity is reached and ovulation starts. © 1957 Nature Publishing Group.