FRAP of Nrg-GFP in embryonic epithelial cells. Face-on views of epithelial cells in wild-type (A), nrx IV (B), cont (C) and Dfvari (D) embryos at stage15. Pre-bleach images are shown on the left. The sections of cell interface that were bleached are indicated with boxes. Images on the right show the recovery of fluorescence 160 seconds after bleaching. Bar: 5 μm.