The effect of ethanol upon early development in mice and rats. XXI. The effect of acute maternal ethanol intoxication upon in vitro hatching of mouse embryos.

The effect of acute ethanol intoxication (ethanol 33% in a.d.) in mice on day 4 of pregnancy (at 9 o'clock a.m.) upon in vitro hatching has been investigated. The embryos were cultured in modified Brinster medium (1963), at 37 degrees C and 5% CO2 in air beginning at 2 o'clock p.m. on day 4 of pregnancy. The control of the developmental stage of embryos from experimental and control groups on day 4 of pregnancy (at 9 o'clock a.m.) showed some numerical differences between the embryos found in early and mid blastocyst stages but no difference between advanced blastocysts. The control after 24 hours of culture showed in both experimental and control groups the presence of expanded blastocysts. No hatched or degenerated embryos were observed. The control at 48 hours revealed the following aspects: the inhibition of hatching revealed by a significantly lower percentage of in vitro hatching (16.3%) in the experimental as compared with the control group (36.6%); the percentage of degenerated embryos is significantly increased in the ethanol group (13%) as compared with the untreated group (6.10%); the percentage of embryos with the zona pellucida fractured does not differ significantly between experimental and control groups. Some problems related to the mechanism of in vitro and in vivo, hatching are discussed.