Pre‐ovulatory and Post‐ovulatory Overripeness

ABSTRACT Experimental work using animal models suggests that alterations of the oocyte during either a delay of ovulation or a delay of fertilization could account for a major percentage of human birth defects. The mechanism by which detrimental changes in the oocyte occur during these delays is not known. Hormonal modifications just prior to ovulation could initiate biochemical processes in the oocyte which proceed to an abnormal sequence of events when ovulation or fertilization does not take place at the optimum time. Alternately, the oocyte may be programmed earlier in its growth phase and undergo degenerative changes if ovulation or fertilization does not occur at the programmed times. A better understanding of the mechanisms involved in both pre‐ovulatory and post‐ovulatory overripeness of the oocyte could ultimately lead to a reduction in the incidence of human developmental anomalies.