Fig. 1. Cort and Fzy are required for the completion of meiosis I and meiosis II. (A-L') Microtubules are red, a 359 bp centromeric repeat unique to the X-chromosome is labeled green and DNA is blue. Smaller panels (A'-L') are higher-magnification views of one of the spindles in A-L, respectively. Mitotic spindles derived from the male pronucleus (when present) are more internal and are not shown in these images. (A-C) Meiosis in wild-type eggs obtained by in vitro activation (A) or from 0-20 minute egg collections (B,C). In metaphase of meiosis I (A), the egg contains a single spindle with two discrete X-chromosome signals representing two pairs of sister chromatids. In metaphase II (B), there are two tandemly arranged spindles, each containing a single X-chromosome signal. In anaphase II (C), sister chromatids separate and both spindles contain two discrete X-chromosome signals. (D-L) Eggs at 0-2 hours from females of the genotypes indicated. (D) In cort^QW55/cort^RH65 (females kept at 29°C for 3-5 days), eggs contain two spindles, each with one X-chromosome, indicating arrest in metaphase II. (E,F) Cks30A^KO/Cks30A^KO eggs with two spindles and either one (E) or two (F) X-chromosomes, indicating a delay as early as metaphase of meiosis II. (G) In fzy⁶/fzy⁷ kept at 29°C, the majority of eggs contain two spindles, both with two X-chromosome signals, indicating arrest in anaphase II. Arrow indicates a small spindle and associated chromatin. (H,I) In cort^QW55,fzy⁶/cort^RH65,fzy⁷ double mutants kept at 29°C, eggs contain either two spindles with one X-chromosome each (H), indicating a metaphase II arrest, or a single spindle with two X-chromosomes (I), indicating a metaphase I arrest. (J-L) Eggs from nosGal4VP16/UAS-cyclinB-TPM-GFP arrest with multiple spindles (J) or with two spindles (K), suggesting a meiosis II arrest, or with a single spindle (L), indicative of a meiosis I arrest.