I investigated the response and sensitivity of lung epithelium to FGF10 that mediates epithelial branching to realize the tissue−specific shape (unpublished data). I demonstrated that uptake of FGF10 by epithelial explants of the pseudoglandular stage lung in Matrigel was highly sensitive over a wide range of FGF10 concentrations in the gel. It was also indicated that ERK activity downstream of FGF10 was dependent on the tissue shape (cellular height and curvature) as well as the FGF10 concentration. The FGF− and tissue shape−dependent acceleration of ERK activity was higher at E13.5 than at E14.5, suggesting that sensitivity to FGF10 gradually decreases during development. To assess how these cellular responses generate lung−specific ordered structure, I constructed a mathematical model in which proliferative and chemotactic activities are determined by the tissue curvature. It was revealed that the branching frequency became shorter as the curvature dependency of activities decreased in the model. This result suggests that the progressive reduction in branch lengths may be regulated through the progressive reduction in FGF10 sensitivity of the lung epithelium (unpublished data). I also constructed another model framework to understand how cellular height is linked to branching formation as a collaborative study with Dr. Katsumi Fumoto at Osaka University (unpublished data). Novel concept of branching mechanism emerging from the spontaneous curvature mediated by apical constriction was described in the model based on his experimental observation.