The in vitro transmission frequency of the t12 mutation in the mouse.

Male mice which are heterozygous for a recessive lethal mutation (+/tL) transmit the tL mutation in non-Mendelian ratios. In the present studies, spermatozoa obtained from +/t12 males were used to fertilize ova from +/t12 females in vitro. The frequency of transmission of the t12 mutation determined from these in vitro studies was compared with the frequency of transmission of this mutation in normal and delayed matings. The data show that the transmission frequency of the t12 mutation, in vitro, is Mendelian and is the same as the transmission frequency of the t12 mutation in vivo when matings are delayed until the time of ovulation.