Rémillard-Labrosse G, Dean NL, Allais A, et al. - In view of the consideration of DNA damage as a major threat to the establishment of healthy eggs and embryos, researchers here examined whether human oocytes possess a checkpoint to prevent completion of meiosis I in case of damaged DNA . Comparison was performed of the influences of DNA-damaging agents with nondamaged control samples in mouse and human oocytes. After informed consent, GV-stage oocytes were received from patients undergoing ICSI cycles; 149 human oocytes were collected over 2 years (from 50 patients aged 27–44 years). DNA-damaging drugs were applied on mice and human oocytes. Whereas oocyte maturation delays or prevents in mouse oocytes in response to DNA damage, most human oocytes harboring experimentally induced DNA damage progress through meiosis I and subsequently form an MII egg, indicating the absence of a DNA damage–induced SAC response. Damaged DNA and chaotic spindle apparatus were identified in analysis of the resulting MII eggs, despite morphologically normal appearance of the oocyte.