Figure 2. Experimental models for the study of EMT. (A) Embryonic mouse palatal shelves were dissected from the 12.5-gestational-day mouse embryos. (B) The palatal shelves are in the horizontal position, but are not touching or fused at this stage. (C) The dissected palatal shelves were placed in organ culture on a filter at the air-media interface for 20 to 72 hrs in the static organ culture model (Kang and Svoboda, 2002). (D) The palatal region can also be cultured in suspension cultures. The palatal region was dissected by a horizontal incision made through the oral opening (A - solid line), and the upper part of the head was resected by a second incision made parallel to the first at the level of the eyes (dashed lines in A and dashed line in B). The tongue and brain tissue were removed from the explants. The palatal explants were placed in 50-mL penicillin bottles (n = 3 to 6 explants/bottle) on a roller bottle culture system (Shiota et al., 1990; Chou et al., 2004). In this system, the palatal shelves fuse in 24 hrs.