The effects of local application of retinoids to different positions along the proximo-distal axis of embryonic chick wings.

Two retinoids, all-trans-retinoic acid and a synthetic analog, TTNPB, were locally applied to different positions along the proximo-distal axis of embryonic chick wing buds using controlled release carriers. Truncations or limbs with duplicated structures across the antero-posterior axis develop after retinoid application to distal positions in buds from stage 20-24 embryos. Phocomelic limbs develop when the retinoids are applied more proximally to buds of stage 23-24 embryos.