Figure 2.

Bivalents were severely misaligned in DKO oocytes. (A) Bivalents in DKO oocytes were misaligned after GVBD. Oocytes were fixed at the indicated times after GVBD and immunostained for DNA and α-tubulin. Representative z-projected confocal images are shown. The yellow asterisks indicate the DKO oocytes containing multipolar spindles. Bar = 20 μm. (B) Cartoon showing the possible chromosome distribution in a spindle during meiosis I. Spindle area was 1:2:1 divided into a central region and the 2 flanking polar regions. Four different Chromosome alignments were distinguished: chromosomes aligned inside the central region (defined as ‘aligned’); no more than 6 chromosomes distributed in the polar regions (defined as ‘mildly misaligned’); more than 6 chromosomes distributed in the polar regions (defined as ‘severely misaligned’); chromosomes were separated (defined as ‘segregated’). (C) Chromosomes in the majority of DKO oocytes were severely misaligned after GVBD. The frequencies of 4 types of chromosome alignments in Ctrl and DKO oocytes at GVBD 8 h and GVBD 16 h are shown. The numbers of oocytes used for analysis are indicated. Data were collected from 3 independent experiments