Fig. 5. M31 and macroH2A1.2 colocalise at the PAR (green is M31, red is COR1 in A and macroH2A1.2 in B and C; long arrow, X chromosome; short arrow, Y chromosome; open arrowhead, M31/macroH2A1.2 PAR focus). (A) Late pachytene XY bivalent showing M31 at the PAR and at the X-centromeric heterochromatin. (B) Same nucleus stained for macroH2A1.2, which localises to the PAR and to the X and Y centromeric heterochromatin. (C) Same nucleus stained for M31 and macroH2A1.2, which shows colocalisation at the PAR and at the centromeric heterochromatin of the X but not the Y chromosome. Bars, 5 µm.