osd1 mutants skip meiosis II.
(A and B) Male meiotic products stained with toluidine blue. (A) A wild-type tetrad. (B) A dyad in the osd1-1 mutant. (C–D) Male meiosis in osd1 is indistinguishable from wild type until telophase I (compare to figure 4), but no figures characteristic of a second division were observed. (C) Pachytene. (D) Diakinesis. (E) Metaphase I. (F) Anaphase I. (G) Telophase I. Two nuclei separated by a band of mitochondria are observed. (H) Metaphase I of female meiosis in osd1.