nc ratio nc ratio the nuclear-cytoplasmic ratio (also variously known as the nucleus:cytoplasm ratio, nucleus-cytoplasm ratio, n:c ratio, or n/c) is a measurement used in cell biology. it is a ratio of the size (i.e., volume) of the nucleus of a cell to the size of the cytoplasm of that cell. nuclear-cytoplasmic ratios. the n:c ratio indicates the maturity of a cell, because as a cell matures the size of its nucleus generally decreases. for example, "blast" forms of erythrocytes, leukocytes, and megakaryocytes start with an n:c ratio of 4:1, which decreases as they mature to 2:1 or even 1:1 (with exceptions for mature thrombocytes and erythrocytes, which are anuclear cells, and mature lymphocytes, which only decrease to a 3:1 ratio and often retain the original 4:1 ratio). an increased n:c ratio is commonly associated with precancerous dysplasia as well as with malignant cells.