Examples of DAPI (blue) and CMA3 (green) stained heterochromatin in the diakinesis of individuals X0-3 (a,a′) and XY-6 (b,b′). White arrows indicate DAPI- or very weak DAPI+/CMA3+ bands on heteromorphic L1, L2 (marked with asterisks *), homozygous M4, S9 (a,a′) and M4-M6 bivalents (b,b′); DAPI+/CMA3+ band in the paracentromeric region on the X chromosomes and DAPI−/CMA3+ on bivalent XY. Silver staining (c–g) of chromosomes in individuals X0-1 (c), X0-3 (d), Co-1 (e), XY-2 (f) and Co-1 (g). The arrows indicate the presence of active NORs coinciding with rDNA clusters (see Table 1). Scale bar = 10 µm.