The effects of retinoic acid on mitosis during tail and limb regeneration in the axolotl larva, Ambystoma mexicanum.

Regenerating tails and limbs of axolotl larvae (A. mexicanum) were studied for overall growth and for mitosis after the animals received intraperitoneal injections of all-trans retinoic acid. Both processes were depressed to approximately the same extent (60-70%). Some mitosis always survived, even when the treatment was in effect during the entire history of the regenerate. The treatment duration was a major variable in the severity of the effect, whereas the post-amputation age of the regenerate was not. In limb regenerates the epithelial cap and the mesenchymal blastema were affected to roughly the same degree.