Fig. 7

Mutations that alter epithelial maintenance also affect epithelial differentiation: (A–H) Cross-sections through the mid intestine of 5 dpf WT and intestinal mutants processed for routine histology and NaPi immunohistochemistry. (A) The WT intestine has a folded epithelium comprised of columnar epithelial cells. (B) Apical NaPi in the WT mid intestine. (C) Although the slj intestine appears undifferentiated, a similar NaPi pattern is present (D). (E) The epithelium in flo also appears undifferentiated, but lacks apical NaPi staining (F). (G) The epithelium of pie larvae is columnar with some folds and thus appears more developed than in slj or flo. (H) Apical NaPi is present in the pie epithelium. (I,K,M,O) Lateral views of the WT, slj, flo and pie intestine. (J,L,N,O) Similar views following detection of enteroendocrine cells (pancreatic polypeptide immunohistochemistry; green) and goblet cells (fluorescent conjugated wheat germ agglutinin lectin; red). (I,J) The WT intestine is folded; pancreatic polypeptide+enteroendocrine cells are restricted to the anterior intestine whereas goblet cells are located in the mid intestine. (K–P) The size of the anterior intestine and the number of enteroendocrine cells is reduced in slj (K,L), flo (M,N) and pie (O,P) mutants, although intestinal morphology is most severely altered in flo and slj compared with pie. Goblet cells appear normal in slj (L) and pie (P) but are absent in flo (N). Arrowheads point to the slj (K) and flo (M) intestine.