P32Autoradiographs of Mouse Testis: Preliminary Observations of the Timing of Spermatogenic Stages

(1) Testis material from mice killed 2, 5, 9 and 12 days after injection of 200 μC of P32 was autoradiographed by the stripping film technique and examined cytologically. (2) Cells at different stages of spermatogenesis were found to take up P32 differently. Some preliminary estimates as to the time taken by various stages of spermatogenesis are (a) from spermatogonial metaphase to early meiotic prophase, between 3 and 9 days; (b) from diakinesis to second metaphase, 4 days or less; (c) from diakinesis to immature sperm, 7 days or more; (d) from spermatogonial metaphase to immature sperm, more than 10 days. (3) Leydig cells were observed to show a strong uptake of P32 within the first 2 days. Some possible explanations for this observation are put forward.