Mast cell–autonomous Notch2 expression is required for mast cell migration toward the epithelium. W^sh/W^sh mice infected with S venezuelensis were intravenously infused with Th2-conditioned Notch2-null or control BMMCs on days 3 and 6 of infection. (A) Notch2-null BMMCs poorly migrated toward the epithelium compared with control BMMCs. Toluidine blue staining followed by eosin staining. Original magnification ×200. (Top) Control BMMCs; (Bottom) Notch2-null BMMCs. (B) The number of mast cells per 10 vcus in the small intestine on day 12 after S venezuelensis infection in W^sh/W^sh mice, without BMMC infusion, with control BMMC infusion, and with Notch2-null BMMC infusion. Data are presented as means ± SEM; n = 3 (control BMMC infusion) and n = 4 (Notch2-null BMMC infusion), P = .004080 (villus, epithelium) and P = .000020 (crypt, epithelium). Note that mast cells in W^sh/W^sh mice infused with Notch2-null BMMCs abnormally resided in the lamina propria, whereas most of those in W^sh/W^sh mice infused with control BMMCs had intraepithelially migrated. (C) Mast cell number in mid to apical side of the epithelial layer was divided with that in the basal side of the epithelial layer. (D) Time course of S venezuelensis egg numbers in the stool. The number of excreted eggs was not significantly different between W^sh/W^sh mice infused with Notch2-null and control BMMCs. Data are presented as means ± SEM.