Specific craniofacial defects induced by jervine in the cultured rat embryo.

The Veratrum-derived steroidal alkaloid, jervine, induces cyclopia and limb malformations in sheep, and various other craniofacial malformations in several other mammalian and avian species. In the present study, the question whether jervine acts directly or indirectly on mammalian embryos to produce malformations and the nature of the target tissue or cells were examined using whole-embryo cultures of the CD rat. Embryos were explanted into culture at the presomite, early neurula stage and cultured in the presence or absence of jervine for 48 hours. Jervine (at 1-5 micrograms/ml) induced an oblong-head appearance and ventrally displaced optic vesicles, with little or no other effects observed on overall growth and development. The specific target tissue in the embryo was found to be the cranial neuroepithelium. This specificity of action is quite unusual since most teratogens examined in whole-embryo culture to date have various nonspecific effects on embryonic growth and differentiation.