Fig. 3. Msi-1 expression correlates spatio-temporally with adult progenitor cells during intestinal remodeling. Cross-sections were immunostained with Msi-1 (A,C,F,H), PCNA (E,I) and IFABP (J) antibodies and stained with methyl green-pyronin Y (B,D,G). (A) Stage 57. The larval epithelium (LE) is negative for Msi-1. (B,C) Stage 60. Progenitor cells of the adult epithelium between the larval epithelium and the connective tissue (CT) are weakly positive for Msi-1 (arrowheads). (D-F) Stage 61. The adult epithelium (AE), where PCNA-positive cells are localized, is positive for Msi-1. The degenerating larval epithelium remains negative. (G-J) Stage 63. The adult epithelium completely replaces the larval one. Msi-1-immunoreactivity is weakly detectable only in the trough of newly formed folds (Fo), where PCNA-positive cells are localized (I; arrows). IFABP immunoreactivity increases in intensity from the crest to the trough of the folds. Bars, 20 µm.