Fig. 4. Cks30A^KO homozygous embryos (40-80 minutes after egg-laying) arrest either with a single metaphase spindle (A) or without assembling a spindle (C). The arrow in A indicates a part of a meiotic spindle that has failed to disassemble. Arrows in C point to separated centrosomes. Embryos are labeled for DNA (green), microtubules (red) and Cnn (blue). (B) Early embryo (0-20 minutes after egg-laying) labeled for DNA (green) and microtubules (red), contains two closely apposed centrosomes, one of which is associated with the paternal chromatin (arrow). This embryo also shows the typical delay in metaphase of meiosis II. (D) FISH labeling of the X chromosome (green) and Y chromosome (red) and microtubules (white) reveals that the metaphase spindle (lower) in Cks30A^KO homozygous embryos contains only the male DNA complement, indicating that pronuclear fusion has not occurred. Polar bodies with only X chromosome signal (green) are at the top. Scale bars: 20 µm.