Figure. 1.

Transwell system. Monolayer epithelial cells are grown to confluence in the insert-well and the cell culture medium level is adjusted such that the monolayer is at the liquid-air interface, allowing the stratification of the cells to occur. (A) Monolayer of oral epithelial cells on insert-well membrane became stratified after grown in liquid-air interface. Some epithelial cells migrated below the membrane and stayed monolayer because being in the liquid phase. (B) Monolayer of oral epithelial cells seeded onto the engineered submucosal tissue (gingival fibroblasts cast in collagen gel on the insert-well membrane) became stratified after grown in liquid-air interface. (A, B) histological analysis with hematoxylin and eosin staining.