Mature mast cells were abnormally accumulated in the lamina propria of the small intestine of Notch2-deficient mice. (A) Sections of the small intestine of N2-MxcKO or littermate control Notch2^flox/flox mice. Toluidine blue staining, followed by eosin. Original magnification ×200. (B) The numbers of mast cells per 10 villus crypt units (vcus) distributing to various layers of the small intestine. Data are presented as means ± SEM; Notch2^flox/flox (n = 10) versus N2-MxcKO (n = 8); P = .000461 (total), P = .000261 (villus, lamina propria), P = .001918 (crypt, lamina propria), P = .046874 (submucosa).