Histological Study of Anophthalmia Observed in Exencephalic Rat Embryos After All-Trans-Retinoic Acid Administration

The purpose of this study is to describe the eye malformations associated with exencephaly observed after retinoic acid (R.A.) administration during gestation in white rat embryos. R.A. suspended in corn oil was given to 13 pregnant rats by gastric intubation. They received various oral doses of R.A. (from 0 to 30 mg/kg b.w. a day) from day 7.5 to 11.5 with an additional dose on day 14.5. No abnormalities have been found in the control groups. The embryos from the treated groups showing anophthalmia and exencephaly were chosen for histological study. The microscopic examination points out dose-dependent abnormalities from absence of eye structures to hypoplastic and atypical more or less compact lens vesicle.