Karyotypes and NOR-bearing chromosomes from three species of octopod gills. a The metaphase plate of O. minor b Karyogram of O. minor from (a) showed that Ag-NOR loci were located on the long arms of metacentric chromosome 3 c The metaphase plate of A. fangsiao d Karyogram of A. fangsiao from (c) showed that Ag-NOR loci were located on the short arms of metacentric chromosome 4 e The metaphase plate of C. chinensis f Karyogram of C. chinensis from (e) showed that Ag-NOR loci were located on long arms of subtelomeric chromosome 23. Arrows indicate the NOR-bearing chromosomes. Scale bars: 5 μm.