Effect of postovulatory oocyte aging on DNA methylation imprinting acquisition in offspring oocytes

Objective: To investigate whether postovulatory aging of oocytes in the mother affects DNA methylation acquisition of imprinted genes in oocytes from the offspring. Design: Randomized research experimental study. Setting: Academic basic research laboratory. Animal(s): Mice. Intervention(s): Fresh oocytes and aged oocytes from mothers were artificially inseminated, and oocytes were collected from the resultant offspring. Main Outcome Measure(s): Methylation status was evaluated at differentially methylated regions (DMRs) in oocytes of maternally imprinted genes Peg3, Snrpn, and Peg1 and paternally imprinted gene H19. Result(s): Our results showed that methylation patterns at DMRs of Peg3, Snrpn, Peg1, and H19 in oocytes from aged-oocyte offspring were mainly normal, with only a small number of oocytes showing aberrant methylation in the DMR of Peg3. Conclusion(s): Postovulatory oocyte aging causes a decline in reproductive outcomes but does not evidently lead to defects in DNA methylation imprinting acquisition in the oocytes from viable offspring. (Fertil Steril (R) 2011;96:1479-84. (C) 2011 by American Society for Reproductive Medicine.)