An essential part of the human diet, retinoic acid is involved in a variety of bodily functions. The substance, for instance, plays a part in the embryonic development of the hindbrain and faciocranial nerves, as well as the differentiation of neurons. Maintenance of healthy skin, hair, mucous membranes, bones, and teeth, are also facilitated by retinoic acid. In fact, the biochemical, which is believed to increase the rate of cell division and turnover, is often used topically in skin-improvement treatments, such as Renova and Retin-A.