Fig. 2. Migrating PGCs exhibit transcriptional repression in mice. (A) (Top) Ser2 phosphorylation (red, left column) in PGCs (green, middle) at E8.75. (Bottom) Magnified images. (B) RNAP II expression (red, left) in PGCs (green, middle) at E8.75. (C) H3K4me2 (red, top, left) and H3K4me3 (red, bottom left) in migrating PGCs (green, middle) at E8.75. (D) Ser5 phosphorylation (red, left) in PGCs (green, middle) at E8.75. (E) BrUTP incorporation (red, left) in PGCs (green, middle) at E8.75. Percentages of BrUTP-weak, stella-positive cells are indicated with the number of cells analyzed in parenthesis (right). (F) Ser2 phosphorylation (red, left column) in PGCs (green, middle) at MS, E7.25, E8.0, E9.5 and E10.5 as indicated. An image for DAPI staining (F, MS) and images merged with Hoecsht staining (A-F, blue) are shown on the right. (G) Ratio of PGCs with strongly positive staining for Ser2 phosphorylation over the course of development. After E8.25 (dotted line), randomly chosen fragments were analyzed. (H) (Top) PGCs (green) stained by H5 (red), H3K9me2 (white) and Hoechst (blue) at E8.0. A white arrowhead denotes a PGC with reduced H3K9me2 but with Ser2 phosphorylation. (Bottom) PGCs (green) stained by H5 (red), H3K27me3 (white) and Hoechst (blue) at E8.75. Pink arrowheads denote PGCs with elevated H3K27me3 but without Ser2 phosphorylation. Scale bars: 100 µm in A, top row; 10 µm in A, bottom row; 10 µm in B-H.