Fig. 5. PGC fragmentation seen by time-lapse imaging. (A) Images from a time-lapse series, showing the progressive fragmentation of a PGC seen in an E11.5 genital ridge explant from a homozygous Cx431KO mouse embryo. The images 1 through 5 are 24 minutes apart. (B) After time-lapse imaging, the genital ridges were stained with a sulforhodamine derivative of valylalanylaspartic acid fluoromethyl ketone that binds caspases 1, 3, 4, 5, 6, 7, 8 and 9 (see Cy3 panel). In the merged image, regions of co-localization of the polycaspase staining (Cy3 panel) with the PGC cell fragments (GFP panel) can be seen. (C) From analysis of the time-lapse movies, the number of apoptotic and mitotic cells was quantitated to generate an apoptotic index comprising the number of apoptotic cells normalized by the number of mitotic cells. This showed a significant increase in apoptosis in the homozygous Cx431KO genital ridges. The number of embryos used in this analysis included seven Cx431 +/+, four Cx431 +/- and five Cx431 -/- embryos. Scale bars: 25 µm.