Which of the following tissues is the most highly radiosensitive?

The correct answer is skin, which is considered the most highly radiosensitive tissue among the options provided. Skin is composed of rapidly dividing cells, particularly in the epidermis. This high rate of cell division makes skin tissues more susceptible to the damaging effects of radiation.

When exposed to ionizing radiation, the DNA in these rapidly dividing cells can be easily affected, leading to increased chances of cell death, mutations, and potential long-term effects such as cancer. The outermost layer of the skin, known as the stratum corneum, is more resistant, but the underlying layers, which are actively proliferating, are vulnerable to radiation damage.

In contrast, salivary glands, nerves, and mature bone exhibit lower radiosensitivity. Salivary glands have some radiosensitivity, but not to the same extent as skin. Nerve tissues are differentiated, meaning their cells are not actively dividing, which reduces their radiosensitivity. Mature bone cells are also relatively radioresistant because they are not frequently dividing; however, some of the cells responsible for bone remodeling can be sensitive under certain conditions. Thus, while all tissues have some level of radiosensitivity, skin stands out as particularly vulnerable due to its cellular characteristics.