Fig. 11

Direct-developing embryos late somitogenesis (Wourms’ stages 29–32). Green cells populate the whole embryonic axis for all the somitogenesis in embryos that do not enter diapause II. Three subsequent stages of the same embryo are reproduced to illustrate how green cells number and density slowly drops as long as development proceeds. a The embryo is composed mainly of green cells, b red cells increased with time and populated the first the somite pairs c somites contain red cells along almost the entire antero-posterior axis of the embryo