Fig. 6. PAR1 and aPKC do not significantly alter cell proliferation. (A-F) Embryos injected at the four- to eight-cell stage with the indicated MO and RNAs (green, A'-D'). GFP-CAAX was used as a lineage tracer for MO injections (B',C'). Embryos were cultured to gastrula stages, fixed, cryosectioned and stained with anti-phospho H3 (P-H3) antibodies (red, A-F; merged images A''-D''). No significant differences were observed in embryos with altered levels of PAR1 or aPKC (compare control MO B with A,C,D), but the number of positive cells was strongly reduced in hydroxyurea (HU)-treated embryos (E) compared with the control embryo (F). No differences in the number of mitotic nuclei were detected between injected and uninjected tissues (marked by lineage tracing) within the same embryo or in different embryos (data not shown). (G-I) Quantification of changes in P-H3-positive cells. Average numbers of P-H3-positive cells per section±s.d. are shown. At least ten embryos were examined for each group.