Effects of hydrocortisone on the development in vitro of the secondary palate in two inbred strains of mice

In organ culture, hydrocortisone in a low concentration significantly retarded palatal development in mice of strain A (susceptible to cortisone-induced cleft palate in vivo), but not in the resistant strain CBA at the same morphological stage of development. The duration of closure was dependent on the developmental stages of the palates at the start of cultivation, palates of younger embryos closing more slowly. These results suggest a strain difference in tissue response to hydrocortisone. It is concluded that the rate of palatal development is not the sole factor determining the genetic differences in hydrocortisone sensitivity and that differences in the metabolism of the teratogen should be considered.