C) Metaphase I (6 hours after GVBD) and metaphase II (16-20 hours after GVBD) chromosome spreads were stained with H3K9me3 antibody and CREST serum to reveal pericentromeric heterochromatin (pink) and the centromere (green), respectively. Chromosomes were stained with Hoechst (blue). Below, schematic representation of a bivalent in metaphase I and a dyad in metaphase II. Enlargement shows the centromere region and a region that we call "chromatid junction" with the corresponding scheme. 