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.
The N:C ratio indicates the maturity of a cell, because as a cell matures the size of its nucleus generally decreases. So, 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.
- Herbert E. Nieburgs (1967). "Nuclear/Cytoplasmic Ratio (N/C) and Nuclear Chromatin". Diagnostic cell pathology in tissue and smears. New York & London: Grune & Stratton. pp. 15–16.
- Takahashi, Masayoshi (1981). Color atlas of cancer cytology (2nd ed.). New York: Igaku-Shoin. pp. 32–34, 50. ISBN 0-89640-050-6.
- John D. Bancroft; Alan Stevens (1982). Theory and practice of histological techniques (2nd ed.). Churchill Livingstone. pp. 438–439.