Alterations in preimplantation in vivo development after preconceptional chronic moderate alcohol consumption in female mice

Although many studies have explored the effects of acute or chronic ethanol exposure during the postimplantation period on embryo/fetal development, f ew reports have described the ethanol. effects on preimplantation embryo de velopment. Little is known about the effects of ethanol consumption prior t o gestation on embryo growth. Recently, we have shown that chronic moderate ethanol intake by prepubertal female mice reduces the ovulatory response a nd impairs in vitro fertilization and in vitro embryo preimplantation devel opment. The purpose of the present work was to evaluate the effects of prec onceptional chronic moderate ethanol ingestion on preimplantation embryo mo rphology and differentiation, the timing of cleavage and embryo growth in v ivo, and to determine the time pattern in which alterations appear. Prepube rtal female mice were treated with 10% (w/v) ethanol for 30 days prior to c onception. After inducing ovulation on day 27 and 29 of the ethanol treatme nt, females were mated with control males and the day of presence of vagina l plug was day 1. On day 1, a decreased percentage of normal fertilized ooc ytes. elevated parthenogenetic oocyte activation and unfertilized eggs with abnormal metaphase II were found in ethanol-treated compared to control fe males. On day while any differences in the total percentage of 2-cell embry os were observed, the treated females had a significantly higher percentage of morphologically abnormal embryos, compared to control females. On day 3 , the preconceptional consumption of ethanol produced significantly reduced percentages of compacted morulae and an increased percentage of uncompacte d morulae. The total percentage of morulae in the treated females was Lower than in controls. On day it, ethanol-treated females showed significantly decreased percentages of hatched attached blastocysts and increased early b lastocyst and morula percentages, compared to controls. Thus, preconception al chronic moderate ethanol ingestion by prepubertal female mice produced r etarded development, impaired blastocyst hatching, abnormal embryo morpholo gy and embryo loss by fragmentation due to alterations induced in the femal e gamete.