Effects of X-rays on BALB/c mouse eggs irradiated during the undivided stage

Mouse eggs from the BALB/c strain present a peculiar sensitivity to X irradiation: when they are irradiated in the oviduct between 17 and 24 hours after HCG injection, a proportion of them, increasing with the dose, are reversibly blocked at the one-cell stage during about twenty hours. This property depends on a maternal effect.