Abstract
Effects of preovulatory overripeness of primary oocytes were studied cytogenetically in 2-cell rat embryos which developed from the ova unduely aged for 48 hours in mature follicles. Both aneuploids and mosaics increased significantly in the experimental group. It was clearly indicated that the delayed ovulation induces nondis j unction and anaphase lag of chromosomes during both the meiotic and first cleavage divisions. A significant increase of polyploidy was also proven as the result of the delay in ovulation. Its causal mechanism was confirmed to be polyspermy.
