Fig. 7. FGF10 controls actin fiber formation (A-I), cell polarity (J-K) and expression of vimentin (L-M) in the developing eyelid epithelium. Whole-mount (A, D-G) and section (B,C,H,I) staining for F-actin of the eyes from wild-type, Fgf10^+/– and Fgf10^–/– fetuses at E15 (A-D,G-M) and E16 (E,F). The upper (B,H) and lower (C,I,J-M) eyelid primordia are shown. (A,D-F) The accumulation of actin fibers at the eyelid leading edge is accelerated, as eyelid closure proceeds. (B,C) Actin fibers are accumulated in the leading edge cells (arrowheads). (G-I) The Rhodamine-phalloidin binding to F-actin is much less on the eyelid margin and in the epithelial leading edge (arrowheads in H and I) of Fgf10-null fetuses. (J-K) Immunofluorescence of -tubulin. (J,K) The localization of -tubulin is indicated by the red, dotted signals. The borders of the cells are shown in green (Bodipy-ceramide). The expression of -tubulin in the inner basal layer (along the dotted line; approximately 17 cells were assessed) appears disorganized and reduced in the Fgf10^–/– eyelid (K). (J',K') Higher magnifications of the eyelid tips shown in J and K, respectively. Weak expression of -tubulin is detected apically in the mutant epidermal cells (arrowhead in K'). (L,M) Immunofluorescence of vimentin. Note that high levels of vimentin protein are expressed in the eyelid mesenchyme (m). (L) In the wild type, vimentin is also localized in the leading edge epidermal cells. (M) Mutant eyelid epidermal cells express much lower levels of vimentin. (L',M') Higher magnifications of the eyelid tip shown in L and M, respectively. The arrowheads indicate the expression of vimentin. All images except A,D-G, which were obtained with a fluorescence stereomicroscope, were captured by laser scanning confocal microscopy. Scale bars: 300 µm (A,D-G); 25 µm (B,C,H,I); 25 µm (J,K); 50 µm (L,M).