Fig. 6. PGC apoptosis and proliferation in E11.5 genital ridges. (A-C) BrdU labeling was used to assess the cell proliferation rate of PGCs in E11.5 wild-type (A) heterozygous and homozygous Cx431KO (B) embryos. BrdU immunodetection using an Alexa Fluor 546 conjugated anti-BrdU antibody (red) showed some regions of co-localization with GFP-expressing PGCs (seen as yellow). No statistical difference was seen in the proliferation rate of PGCs in wild-type versus heterozygous/homozygous Cx431KO mouse embryos (C). Note that the data are normalized to the frequency of BrdU-positive PGCs in wild-type embryos. This analysis included eight Cx431 +/+, 25 Cx431 +/- and six Cx431 -/- genital ridges. (D-F) TUNEL labeling in E11.5 genital ridges from wild-type (D) and Cx431KO (E) mouse embryos. TUNEL labeling is visualized by BrdU incorporation, detected using Alexa Fluor 546 conjugated anti-BrdU antibody (red). In the genital ridges from the KO mouse embryo, we noted many regions containing TUNEL-positive GFP-expressing PGCs (see white arrows in E). Quantitative assessments showed a significant increase in TUNEL-positive PGCs in the homozygous Cx431KO embryos (F). Note that the data are normalized to the frequency of TUNEL-positive PGCs in wild-type embryos. This analysis included 12 Cx431 +/+, 16 Cx431 +/- and 10 Cx431 -/- genital ridges. Scale bars: 100 µm.