The D-chiro-inositol–to–myo-inositol ratio is regulated by an insulin-dependent epimerase. Enzyme activity varies among tissues, likely owing to the specific needs of the two different molecules. We hypothesize that in the ovaries of polycystic ovary syndrome patients, epimerase activity is enhanced, leading to a local myo-inositol deficiency which in turn is responsible for the poor oocyte quality. (Fertil Steril 2011;-:-–-. 2011 by American Society for Reproductive Medicine.)
