Diagram showing a nucleus with CBs, locus signals, a nucleolus, and a CB–locus association. The dashed line around the CB represents the effective area of a CB that is available for colocalization if locus signals are considered points. The nucleoplasmic area is essentially equal to the area of the nucleus minus the nucleolar area. Average values were nuclear area, 133.7 μm2; nucleolar area, 10.9 μm2; nucleoplasmic area (AN), 123 μm2; and effective CB area (Acb), 0.66 μm2.