Retinoic acid retards fetal and hindlimb skeletal development asymmetrically in a retinoic acid-induced clubfoot model

Retinoic acid (RA) has been shown to induce congenital clubfoot in animal models, but it is unknown whether the effect of RA on the formation of clubfoot in vivo results from generalized growth retardation or from the specific effects of hindlimb skeletal development. Our experimental research was based on a clubfoot model treated by maternal administration of RA (120, 130 or 140 mg/kg body weight) as an intragastric dose on embryonic day 10 (E10), and a control group was administered with an equivalent dose of solvent. Prenatal RA exposure reduced fetal body weight, length and skeletal ossification of the hindlimb compared with the control fetuses in a dose-dependent manner. The normal development curves indicated that the RA-exposed fetuses showed delayed increase in body weight and skeletal ossification development. However, there was no uniform effect on the skeletons of the hindlimb, not least retardation in ossification and induction malformation on the talus and calcaneus. Our results demonstrated that prenatal RA exposure had retardation effects on the developing hindlimb skeleton that was independent of those on the overall fetal growth. The normal skeletal ossification showed that the talus and calcaneus were poorly ossified and they were delayed by almost one day in the RA 120 mg/kg group. Therefore, during the susceptible stages, different regions of the limb bud responded differently to the teratogenic effects of RA.