The effect of vitamin A on fusion of mouse palates. II. retinyl palmitate, retinol, and retinoic acid in vitro.

A fixed-exposure culture technique is described using palatal shelves removed from mouse fetuses on day 14 of pregnancy. In this technique growth is eliminated as a possible variable. The addition of retinyl palmitate, retinol, or retinoic acid to culture medium at concentrations similar to those found associated with cleft palates produced in vivo after dosing dams with vitamin A on day 14 prevented fusion of explanted shelves in vitro after a 24-hour exposure period. Retinoic acid prevented fusion of explants after as little as 4 hours exposure. Retinoic acid was more active in vitro than retinol, which was itself eight to ten times more active than retinyl palmitate. An explanation of the effect of vitamin A on the fusing mouse palate is give based on altered glycoprotein synthesis.