Which of the following is (are) relatively insensitive to radiation?

• A. Nerve tissue
• B. Reproductive cells
• C. Epithelial tissue
• D. Immature sperm cells

Answer: (A)

Tissues differ in sensitivity to radiation based on how actively the cells divide and how differentiated they are. Nervous tissue is relatively insensitive because neurons and most glial cells are largely non-dividing and highly specialized, with minimal cell turnover. That low mitotic activity means there are fewer targets for radiation to disrupt leading to cell death at typical diagnostic doses.

In contrast, tissues with rapid turnover or active germ cell populations are more radiosensitive. Reproductive cells, especially immature sperm cells (spermatogonia), are continually dividing and differentiating, making them highly susceptible to radiation damage. Epithelial tissues also renew themselves quickly, so they tend to be more sensitive to radiation as well.

So nervous tissue stands out as the most relatively insensitive choice among those listed.