Fig. 7. MAP kinase signaling is elevated in the pole cells compromised for pgc function. (A,B) Wild-type embryos were stained with anti ERK antibodies and signal was visualized with DAB. (A) A syncytial blastoderm embryo displays increased levels of staining at both the termini. Very little, if any, signal is detected in the pole cells. (B) Signal specific for anti-ERK antibodies completely disappears by cellular blastoderm stage. (C,D) Pre-syncytial cycle 10 embryos co-immunostained with monoclonal anti-ERK antibody (green) and anti-Vasa antiserum (red). (C',D') The same embryos as in C and D labeled with only anti-ERK antibody. Pole cells from the wild-type embryo (C and C') have only a low level of anti-ERK specific signal whereas pole cells compromised for pgc function (D,D') have much higher levels.