OsMTOPVIB is essential for bipolar spindle assembly. (A) The process of meiotic spindle assembly in OsmtopVIB. Chromosomes were stained with DAPI (blue), and microtubules were immunostained with α-tubulin antibody (green). (Scale bars: 5 μm.) (B) Products of meiosis in wild type and OsmtopVIB. In wild-type meiocytes, dyads at telophase I and tetrads at telophase II are shown. In OsmtopVIB, chromosomes are pulled to 2, 3, or 4 groups at telophase I. Tetrads, hexads, and octads are shown in OsmtopVIB at telophase II. (Scale bars: 5 μm.) (C) Frequencies of meiotic products in wild-type and OsmtopVIB meiocytes. At telophase I, 100% dyads are in wild type, while 24.27% dyads, 70.29% triads, and 5.44% tetrads are in OsmtopVIB (n = 515). At telophase II, 100% tetrads are in wild type (n = 505), while 14.16% tetrads, 19.30% pentads, 58.23% hexads, 2.12% heptads, and 6.19% octads are in OsmtopVIB (n = 565).