Microinjection of cultured rat embryos: studies with retinol, 13-cis- and all-trans-retinoic acid.

Retinol, all-trans-retinoic acid or 13-cis-retinoic acid were intraamniotically microinjected in rat embryos on day 10 of gestation and cultured until day 11.5. A comparison of the concentration-effect relationships of the retinoids showed that the dysmorphogenic effects were qualitatively similar for all three, but were elicited by a low concentration of all-trans-retinoic acid (250 ng/ml), a 6- to 7-fold higher concentration of 13-cis-retinoic acid and an approximately 16-fold higher concentration of retinol. After microinjection of 2,000 ng/ml of retinol, no dysmorphogenesis was observed but instead an increase in all growth parameters as compared to the controls.