Fig. 7. How late is maternal Hunchback expressed in Nasonia and Drosophila? (A) Zygotic expression of Nasonia Hunchback during the onset of cellularization and the beginning of posterior cap expression. (B) Lack of residual maternal Hunchback expression in similarly aged hunchback^hl mutant embryo. The embryos in A and B were from a very tightly staged collection, and, therefore, are very similar in age (see Materials and methods). (C) Zygotic expression of Drosophila Hunchback, during the onset of cellularization and the beginning of posterior cap expression. (D) Residual maternal expression in nuclei at the surface of a Drosophila embryo lacking zygotic hunchback, very similar in age to the embryo in C. The A,B and C,D embryo pairs were photographed together in the same frames.