What is the name of the law that explains increased radiosensitivity in tissues with high mitotic activity and many undifferentiated cells?

• A. Law of Bergonie & Tribondeau
• B. Law of Reciprocity
• C. Inverse Square Law
• D. X-ray Summation Law

Answer: (A)

Radiosensitivity varies with how a cell behaves in division and differentiation. The law named for Bergonie and Tribondeau states that cells are most radiosensitive when they divide rapidly, are poorly differentiated (undifferentiated), and have a long future of potential division. Because these cells spend more time in vulnerable phases of the cell cycle and have extensive reproductive capacity, ionizing radiation is more likely to cause damage that leads to cell death or malfunction. This explains why tissues with high mitotic activity, like bone marrow, intestinal epithelium, and reproductive cells, are more susceptible to radiation, while mature, differentiated tissues such as muscle and nerve are comparatively resistant. Other options describe exposure relationships or physical dose effects rather than cellular radiosensitivity, so they don’t fit this specific concept.