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 preconceptional alcohol ingestion by females has had little investigation. We have recently shown that chronic 10% (w/v) ethanol intake by young female mice reduces the ovulatory response and impairs the quality of the oocytes. The aim of this study was to investigate the effects of 10% ethanol administration for 30 days on immature female mice on the day of in-vitro fertilization (day 1) and on preimplantation embryo development. Female mice were ovulated 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 parthenogenetic activation compared to the control females. An increased percentage of fragmented oocytes was found after insemination, compared to control females. When the embryos were cultured, the percentage of 2-cell (day 2), 4-cell (day 3) embryos, and compacted morulae (day 4) was significantly reduced in treated females, compared to control females. On day 5, we found a highly 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 and 7 (blastocyst stages). An increased percentage of morphologically abnormal embryos was found on days 5 and 6 in ethanol-treated females compared with controls. We conclude that chronic moderate ethanol ingestion by young female mice results in decreased fertilization, embryo growth retardation, cleavage arrest, and abnormal embryo development in vitro.