Deleterious effects of chronic moderate alcohol intake by female mice on preimplantation embryo growth in vitro

The susceptibility of preimplantation stages of embryo development to preco nceptional alcohol ingestion by females has had little investigation. We ha ve recently shown that chronic 10% (w/v) ethanol intake by young female mic e reduces the ovulatory response and impairs the quality of the oocytes. Th e aim of this study was to investigate the effects of 10% ethanol administr ation for 30 days on immature female mice on the day of in-vitro fertilizat ion (day 1) and on preimplantation embryo development. Female mice were ovu lated on days 27 and 29 of ethanol treatment and in-vitro fertilization was performed 16 h post-human chorionic gonadotrophin administration (day 30). The oocytes from the ethanol-treated females inseminated with spermatozoa from control males, showed a significantly higher percentage of parthenogen etic activation compared to the control females. An increased percentage of fragmented oocytes was found after insemination, compared to control femal es. When the embryos were cultured, the percentage of 2-cell (day 2), 4-cel l (day 3) embryos, and compacted morulae (day 4) was significantly reduced in treated females, compared to control females. On day 5, we found a highl y significant decreased percentage of early and expanded blastocysts in the ethanol-treated females. The percentage of hatching and hatched (extruded) blastocysts was also reduced significantly in treated females at days 6 an d 7 (blastocyst stages). An increased percentage of morphologically al,norm al embryos was found on days 5 and 6 in ethanol-treated females compared wi th controls. We conclude that chronic moderate ethanol ingestion by young f emale mice results in decreased fertilization, embryo growth retardation, c leavage arrest, and abnormal embryo development in vitro.