A patient on chemotherapy presents with signs of drug toxicity. Which tissues are most likely affected?

Chemotherapy agents are designed to target rapidly dividing cells, which is characteristic of cancer cells. However, these agents also affect other normal tissues that have high turnover rates. The most commonly affected tissues during chemotherapy include the bone marrow, gut mucosa, and hair follicles.

The bone marrow is crucial for producing blood cells, including red blood cells, white blood cells, and platelets. Chemotherapy can lead to myelosuppression, resulting in anemia, increased risk of infections due to neutropenia, and bleeding complications due to thrombocytopenia.

The gut mucosa is also affected due to its rapid cell turnover, leading to side effects such as mucositis, nausea, and diarrhea, which are common issues faced by patients undergoing chemotherapy.

Hair follicles are similarly impacted, as they are also composed of rapidly dividing cells. This often results in hair loss (alopecia), which is a well-known side effect of many chemotherapy drugs.

Considering these points, the correct answer identifies the tissues most vulnerable to the toxic effects of chemotherapy. The other options primarily involve organs and tissues that do not have the same level of cell turnover as those listed in the correct answer, making them less likely to show signs of drug toxicity in the context of chemotherapy.