Correlation between cytological and morphogenetic effects of acute X-irradiation of preimplantation mouse embryos cultured in vitro.

Inhibition of cavitation by acute X-irradiation of 2-cell stage eggs was due to the early killing of the cells. Eggs in which cavitation did take place had a smaller number of cells due mainly to mitotic delay, leading to lack of inner cell mass (ICM) and its derivatives in further development. A similar effect is responsible for the inhibition of ICM formation after irradiation of morulae.