Which cells are among the most radiosensitive, particularly during active growth and development?

• A. Lymphocytes
• B. Neurons
• C. Muscle cells
• D. Epithelial cells

Answer: (A)

Radiosensitivity tracks how actively a cell divides and how differentiated it is. Lymphocytes fit this pattern perfectly: they are small, undifferentiated white blood cells that divide rapidly. When radiation hits, DNA damage disrupts replication, and these cells are prone to apoptosis, making them extremely vulnerable. This is especially true during periods of active growth and development when many cells are proliferating, so lymphocytes stand out as among the most radiosensitive cell types. In contrast, neurons are mostly non-dividing and highly differentiated, and muscle cells divide little, so they are much less sensitive. Epithelial cells do renew, but their turnover isn’t as rapid or as universally radiosensitive as that of lymphocytes, so they’re not as highly sensitive in this context.