Geminin injection induces an extra syncytial division, but does not affect interphase length after the MBT. (A) Histone-GFP–expressing embryos were injected at one pole (left) during cycle 13 with Geminin. Note that nuclei synchronously and prematurely enter mitosis 14 in the injected region. (B) Histone-GFP–expressing embryos were injected with Geminin during interphase 14 before cellularization. Bifurcated arrows highlight normal anaphases during mitosis 14 and arrows show unreplicated chromosomes in mitosis 15 that fail to reach the metaphase plate. (C) Quantification of interphase and mitotic duration from embryos as in A and B. Average interphase and mitotic times are shown for cycle 14 (n = 13 embryos) and cycle 15 in domain 5 (n = 33 embryos). Error bars represent SD.