Fig. 5. Analysis of periderm cell fate. Periderm cells were labeled with CCFSE as described in the Materials and methods, and palates were cultured for 8 hours. Samples were analyzed every 2 hours. At the beginning of culture (2 hours), periderm cells were confined to the MES middle line between the two basal MEE; cell death was not detected at this time. As fusion proceeded (4, 6 and 8 hours), accumulation of labeled cells occurred at the apex of the MES, constituting a large proportion of epithelial triangle cells. Most labeled cells died within the epithelial triangles (yellow cells; see also Fig. 5). As noted here, basal MEE cells appeared to die in situ within the epithelial pearls (arrows at 8 hours; compare with Fig. 1). Arrowheads indicate autofluorescent erythrocytes. These experiments were repeated more than three times at least in triplicate for each condition. Scale bar: 100 µm.