Fig. 2. Both HB-EGF null embryos and embryos with an uncleavable mutant form of HB-EGF show delays in eyelid closure. (A,B) Representative whole-mount lacZ stained (black arrow) HB^del/+ eyelids (A) and HB^del/del eyelids (B) at E15.5. Scale bar: 500 µm for A and B. (C) Schematic diagram showing how the progression of eyelid closure was measured. (D) Comparison of the progression of eyelid closure along the long axis (left panel) and the short axis (right panel) between HB^del/+ (blue dots, n=19) and HB^del/del (orange dots, n=20) embryos. (E) Comparison of the progression of eyelid closure along the long axis (left panel) and the short axis (right panel) between HB^uc/+ (blue dots, n=18) and HB^uc/uc (yellow dots, n=16) embryos. Horizontal bars in the graphs indicate the mean value (D,E).