THE CHRONOLOGY OF DNA SYNTHESIS, MEIOSIS AND SPERMIOGENESIS IN THE MALE MOUSE AND GOLDEN HAMSTER

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Abstract
A method is described for estimating the duration of DNA synthesis in mammalian spermatocytes. This duration is about 29 and 40 hr in the male mouse and golden hamster, respectively. The duration of spermiogenesis and various stages of meiosis was also studied. The spermatocyte DNA was labelled with thymidine-H3 and the kinetics of the labelled cells was followed radioautographically until the formation of mature spermatozoa. In both animals leptotene lasts for less than 3 days, zygotene shorter than 1 day and pachytene as long as 7-8 days. Transition from diplotene to anaphase II is extremely rapid and requires about 1 day or less. Spermiogenesis is completed in approximately 14-16 days. Labelled mature spermatozoa of the mouse and those of the golden hamster appear at 26.5 ± 0.5. and 25.5 ± 0.5 days postlabelling, respectively.