Fig. 1. CI in N. vitripennis. (A) Category 1. In 5% of N. vitripennis CI embryos, chromosome segregation is normal, indicating that the egg was unfertilized. (B,C) Category 2. In 26% of N. vitripennis CI embryos, the paternal genome is not segregated. (B) Nuclear cycle 2, there are two normal nuclei and one highly condensed nucleus (arrow). (C) Nuclear cycle 3, there are four normal nuclei and one highly condensed nucleus (arrow). (D-F) Category 3. In 48% of N. vitripennis CI embryos, the paternal genome segregated to one daughter nucleus at the end of nuclear cycle 1. (D) Nuclear cycle 1, one nucleus is normal whereas the other appears to be a composite of two nuclei (arrowhead). (E) Nuclear cycle 2, two normal nuclei are present and the composite nucleus attempts to divide (arrowhead). (F) Nuclear cycle 2, two normal nuclei are present and the composite nucleus divides to give one normal-looking nucleus (bottom of bracket), one misshapen nucleus (top of bracket), and one highly condensed nucleus (middle of bracket). (G,H) Category 4. In 22% of N. vitripennis CI embryos, the paternal genome is mis-segregated to both daughter nuclei. (G) Nuclear cycle 2, a chromatin bridge connects the two daughter nuclei. (H) Nuclear cycle 3, all four nuclei are misshapen and of different sizes. (I) Nuclear cycle 3 uninfected control embryo, all nuclei are of uniform size and shape. (J) Nuclear cycle 12 CI embryo; 78% of CI embryos reach at least the syncytial blastoderm stage. (K) CI embryo in which development has arrested; 22% arrested with a few, highly condensed nuclei. Bars, 8 µm (A-I).