Oral antioxidants counteract the negative effects of female aging on oocyte quantity and quality in the mouse

This study aims to compare the effect of early and late onset administration of oral antioxidants on number and quality of oocytes retrieved from aged mice after exogenous ovarian stimulation. Control hybrid females were fed a standard diet supplemented or not supplemented with pharmacological doses of vitamins C and E either from the first day of weaning or from the age of 32 weeks until they were autopsied at the age 40–42, 50–52, or 57–62 weeks after exogenous ovarian stimulation. Analysis of chromosomal distribution, DNA organization and cellular morphology was performed in ovulated cumulus‐enclosed and ‐free oocytes, ovarian non‐germinal vesicle oocytes enclosed by or free of mucous cumulus cells and in vitro‐matured ovarian germinal–vesicle oocytes. Both early and late onset administration of oral antioxidants counteracted the negative effects of female aging on number of ovarian oocytes and total percentage of oocytes retrieved from oviducts and ovaries exhibiting a normal distribution of chromosomes in the metaphase‐II plate and/or morphological traits of apoptosis. Although both early and late onset administration of oral antioxidants can counteract the negative effects of female aging on number and quality of oocytes, transference of these results to human beings should be made with caution because of the potential side effects of high doses of vitamins on reproductive function as well as many other undesirable systemic disorders. Mol. Reprod. Dev. 61: 385–397, 2002. © 2002 Wiley‐Liss, Inc.