In terms of radiosensitivity, which tissue type is least sensitive?

Highly differentiated tissues are characterized by their specialized functions and are typically composed of cells that have lower mitotic activity. This lower turnover rate, coupled with their specialization, renders them less sensitive to radiation compared to other tissue types. Their complexity and the fact that they are generally in a non-dividing state contribute to their relative resistance to radiation damage.

In contrast, rapidly dividing tissues, undifferentiated cells, and moderately differentiated tissues often possess higher radiosensitivity because they are more actively undergoing mitosis. Cells that are in the growth cycle, especially those that are rapidly dividing or less differentiated, are more vulnerable to the effects of radiation since radiation primarily damages DNA during these active phases of cell division.

Thus, the distinction lies in the degree of differentiation and the rate of division, with highly differentiated tissues being the least sensitive to radiation exposure due to their stable, specialized nature.