Fig. 5. Intestinal phenotype of mib^ta52b homozygotes. (A,B) 2F11 staining in the intestinal bulb, comparing three representative pairs of wild-type (A) and mib^ta52b (B) specimens at 3 days. The vast majority of epithelial cells are switched to a secretory fate in mib^ta52b. (C,D) At the same time, the number of cells expressing DeltaD (zdd-2 antibody, green, indicated by arrows in C) is greatly increased in the mutant. Membrane localization of DeltaD in mib^ta52b reflects the failure of Mib-dependent Delta internalization. (E,F) 4E8 staining (green) shows deficit of absorptive cells in three-day mib^ta52b. (G,H) 2H9 staining (green) shows abnormal epithelial cell polarity in mib^ta52b. (I,J) Staining of the basement membrane with 5F11 (green) is also fainter in mib^ta52b than in wild-type. (K,L) At 4 days, many dying cells are seen in mib^ta52b (L) but not in wild type (K). (A-L) TOPRO-3 nuclear stain is red.