When do cells generally begin to show signs of injury after radiation exposure?

Cells generally begin to show signs of injury after radiation exposure within hours. This is due to the fact that radiation causes immediate changes at the molecular and cellular levels. When cells are exposed to ionizing radiation, such as X-rays or gamma rays, it can lead to damage in DNA and other critical cellular structures.

The initial response to this damage may manifest rapidly, often within hours post-exposure, as cells attempt to repair the inflicted harm. This includes the activation of various cellular repair mechanisms. Depending on the extent of the damage and the type of cells involved, signs of injury—such as cell death, impaired function, or abnormal growth patterns—can start to become apparent during this timeframe.

In contrast, the other options reflect longer durations after exposure when signs of injury may become more pronounced but do not capture the initial and immediate nature of the cellular response after radiation exposure.