INTERDIGITAL SOFT-TISSUE SEPARATION INDUCED BY RETINOIC ACID IN MOUSELIMBS CULTURED IN-VITRO

The temporal pattern of separation of the soft tissue between mouse di gits was examined in an organ culture model system. Mouse limbs of dif ferent gestational age were cultured in vitro and the pattern of separ ation of the digits characterized. By gestational day 12.5 (E12.5) the limbs were committed to undergo separation of the soft tissue in the interdigital space when cultured in vitro. Prior to E12.5 digital sepa ration did not occur and the limb tissues were not committed to this p rocess. The addition of 10(-7) M retinoic acid (RA) to the media of E1 2 limbs was capable of inducing digit separation in the uncommitted li mbs. Both the soft and hard tissue development of digits formed in vit ro for either committed limbs or uncommitted limbs induced with RA was similar to the in vivo pattern.