Under the Law of Bergonié and Tribondeau, which cells are most radiosensitive?

• A. Nerve and muscle cells
• B. Mature, differentiated, slowly dividing cells
• C. Immature, undifferentiated, rapidly dividing cells
• D. All cells equally sensitive

Answer: (C)

Radiosensitivity depends on how differentiated a cell is and how actively it divides. Under Bergonié and Tribondeau, cells are most sensitive when they are immature and undifferentiated and capable of many future divisions. Because radiation damages DNA, cells that are rapidly replicating have less time to repair that damage before they divide, making them more likely to die or pass on mutations. In contrast, mature, differentiated cells that divide slowly, such as nerve and muscle cells, have limited proliferative activity and are relatively radioresistant. The idea that all cells are equally sensitive doesn’t fit the observed pattern of tissue response, since tissues with high turnover (like those with rapidly renewing cells) are much more affected than those with low turnover. This concept explains why rapidly dividing, immature cells are the most radiosensitive.