Abstract
In organ culture sodium salicylate and acetylsalicylic acid in a 1.4 mM concentration caused prolongation of the time needed for the closure of the mouse secondary palate. The response of Strain A and the hybrids CBA×A was more distinct than that of Strain CBA. The mitotic rate, calculated from serial sections, was significantly reduced in the salicylate‐treated palatal shelves in both strains. The extrapolation of the results to an in vivo situation is discussed in the light of different theories of the mechanism of cleft palate formation.