ABSTRACT
Figure 5 Phocomelia. Rat fetus, day 21 of pregnancy, 40 mg all-trans-RA/kg body wt on day 12 orally.
The teratogenic of vitamin A and the retinoids shows species variation (fable 4). The most drastic differences in this regard were observed with
13-cis-~RA: teratogenic doses in the human were below mg/kg/day, in the monkey between 2.5 and 5 mg!kg/day, and in the mouse 100 mg/kg/day (48). The rat proved to be as insensitive as the mouse, whereas the rabbit and hamster were more sensitive animal species toward 13-cis-RA teratogenesis than the mouse ( 49,50). Also, the teratogenicity of retinol exhibits great species variation, which is similar but not as drastic as that of 13-cis-RA. These differences are much less pronounced, in some cases even reversed, all -trans-RA
and metabolism (51-53).
