the nucleolar association of chromosome 9 heterochromatin is less constant : in 42.3 per cent of the nuclei both segments are associated with the nucleolus , in 39 per cent of the nuclei only one heterochromatic segment presents such an association , and in 18.7 per cent neither of the two heterochromatic segments is in nucleolar association .
C0019397
heterochromatin
C0007610
nuclei