Induction of meiosis in fetal mouse testis in vitro by rete testis tissue from pubertal mice and bulls.

To test whether a meiosis-inducing substance (MIS) is responsible for the induction of meiosis in the testis at puberty, pubertal mouse rete testis was grown with (1) fetal undifferentiated mouse testis attached to the other side of a filter and (2) the used medium obtained from culture of the rete testis of a pubertal bull for 2 days. In both systems meiosis was induced in the fetal testis showing that MIS is not species specific. No meiosis-preventing effect was seen and it is concluded that meiosis in the testis is triggered at puberty as a result of the activity of the MIS concomitant with decreased activity of the meiosis-preventing substance.