Fig. 7. Fate mapping of the FGF2-treated canal pouch. Otocysts were treated with either BSA (A-C) or FGF2 (D-F) at E4, and DiI was delivered to the 12 o'clock position of the canal pouch at E5; inner ears were harvested at E9. (G-I) FGF2 bead implantation and DiI injection were carried out at the same time, at E5. A, D and G show the location of DiI injection. The same three specimens shown in A, D and G are shown on E9 as fluorescent (B,E,H) or combined fluorescent and bright field images (C,F,I). DiI-labeled cells are associated with the common crus only in BSA-treated specimens (B,C; arrows), whereas some DiI-labeled cells in FGF2-treated specimens are associated with the canals (E,F,H,I; double arrows). Arrowheads indicate cells outside the membranous labyrinth and green arrows indicate the junction of the anterior and the posterior canals. A, anterior; D, dorsal; L, lateral; P, posterior. Scale bar in A: 200 µm for A-I.