Which factor is NOT part of the Bergonie and Tribondeau law?

• A. Radiosensitivity depends on the degree of mitotic activity in tissue
• B. Radiosensitivity depends on the age of the individual cells
• C. Radiosensitivity depends on the number of undifferentiated cells in tissue
• D. Radiosensitivity depends on the length of time the cells stay in active proliferation

Answer: (B)

Radiosensitivity, according to Bergonié and Tribondeau, increases in cells that are less differentiated, divide rapidly, and have a long remaining capacity to divide. This means tissues with many undifferentiated cells and high mitotic activity, and those with a long future of proliferation, are more radiosensitive. The age of the individual cells isn’t listed as a separate factor in the law; while younger, less mature cells can be more radiosensitive in practice, the law specifies differentiation, mitotic activity, and remaining proliferative future as the determinants. Therefore, the age of the individual cells is not part of the Bergonié and Tribondeau criteria.