| Abstract: | The duration of the early stages of meiotic prophase was determined in the oogenesis of T. cristatus cristatus by means of autoradiography. The oocytes were being investigated during 39 days from the moment of 3H-thymidine injection. It was shown that preleptotene lasts 1--2, leptotene ca. 4, zygotene 5 and pachytene 26 days. When studying the preparations obtained 1 day after the injection of 3H-thymidine, the silver grains were found to be localized over the nuclei at all stages of meiotic prophase; this suggests the amplification of rDNA which begins in leptotene-zygotene and ends in early diplotene. |
