Fig. 5. Msi-1 expression correlates with adult progenitor cells during gastric remodeling. Cross-sections were immunostained with Msi-1 (B,C,G,J,L), PCNA (D,F,K) and Pg (I) antibodies, and stained with methyl green-pyronin Y (A,E,H). (A-D) Stage 60. Progenitor cells of the adult epithelium appear in the basal region of larval glands (L-GE) and are positive for Msi-1 (A,B; arrowheads). Msi-1 immunoreactivity is localized in the cytoplasm of these cells, which are actively proliferating (C,D; arrows). L-SE, larval surface epithelium; M, muscles. (E-G) Stage 61. The adult epithelium (AE) is positive for Msi-1, whereas the larval epithelium (LE) remains negative. CT, connective tissue. (H-J) Stage 62. The adult epithelium completely replaces the larval one and begins to differentiate into the surface (A-SE) and glandular epithelia (A-GE) expressing Pg (I). Msi-1 immunoreactivity becomes weak. (K,L) Stage 66. Msi-1 immunoreactivity is weakly detectable only in the neck region of glands, where proliferating cells are localized (arrows). Bars, 20 µm.