Long-Term Effects of Postovulatory Aging of Mouse Oocytes on Offspring: A Two-Generational Study

Aims of this study were to analyze the long-term effects of postovulatory aging of mouse oocytes on 1) reproductive traits of parental (F 0 ) and first (F 1 )-generation females (pregnancy rate, gestation length, litter size, perinatal death, and sex ratio of offspring) and 2) developmental and behavioral variables of F 1 and second-generation (F 2 ) offspring (birth weight and weight gain during preweaning development, postnatal day of attainment of immediate righting, spontaneous motor activity, and passive and active conditioned learning ability). Hybrid (C57BL/6JIco × CBA/JIco) females were artificially inseminated at 13 h (control group) or 22 h (oocyte-aged group) after GnRH injection. Experimental (oocyte-aged group) F 0 females exhibited lower pregnancy rate, shortened gestation length, decreased litter size, higher perinatal death of their pups, and increased percentage of male offspring compared to control F 0 females. Postovulatory aging of oocytes was also associated with increased number of growth-retarded pups, delayed development of the righting reflex, and higher spontaneous motor activity and emotionality of F 1 offspring. Postovulatory aging of F 0 oocytes did not affect birth weight, weight gain during preweaning development, passive and active conditioned learning ability of F 1 offspring, or reproductive traits of F 1 females or developmental and behavior variables of F 2 offspring.