Fig. 2. Developmental expression of Msi-1 mRNA during metamorphosis. Cross-sections of the small intestine (A-E) and the stomach (F-I) were hybridized with the antisense (A,C,E,F,H,I) and sense (D) probes and stained with methyl greenpyronin Y (B,G). (A) Stage 58. No specific signals are detectable. (B-D) Stage 61. Adult progenitor cells (arrowheads) between the larval epithelium (LE) and the connective tissue (CT) are positive. No signals are detectable in the control section (D). (E) Stage 65. The adult epithelium (AE) is almost negative except for very weak signals in the trough of intestinal folds (Fo). (F) Stage 58. No specific signals are detectable in the larval surface (L-SE) and glandular epithelia (L-GE). (G,H) Stage 61. Signals are localized in adult progenitor cells. (I) Stage 65. The adult surface (A-SE) and glandular epithelia (A-GE) are almost negative. Weak signals in the neck region of glands are nonspecific. Bars, 20 µm.