[Critical time for developmental eye abnormalities induced by retinoic acid in mouse fetuses]

To identify the critical time for developmental eye abnormalities, pregnant C 57 BL/6 NJcl mice were injected intraperitoneally once with 12.5 mg/kg of retinoic acid on days 7 (day-7 group), 8 (day-8 group), 9 (day-9 group), 10 (day-10 group), and 11 (day-11 group) of pregnancy. Each group consisted of 5 pregnant mice. The fetuses were observed grossly on day 18 of gestation, and the eyes were examined histologically in serial sections. Various gross malformations such as microphthalmos, cleft lip and palate, and central nervous system anomalies were observed in the day-7 group. However, microphthalmos was the only gross malformation found in the day-8 group, and there were no gross malformations in the other 3 groups. The histological examination indicated that the critical time for anophthalmos was day 7 of gestation or earlier because of its appearance in the day-7 group alone. The critical time for microphthalmos, faulty closure of the embryonic fissure, aphakia, and faulty separation of the lens vesicle was day 8 of gestation or earlier considering their occurrence in both day 7 and day 8 groups, and the time for goniodysgenesis was day 9 of gestation or earlier because of its appearance in the day 7, day 8, and day 9 groups.