According to the Law of Bergonié and Tribondeau, ionizing radiation is more effective against cells that are:
a. actively mitotic and differentiated and have a long mitotic future.
b. actively mitotic and differentiated and have a short mitotic future.
c. not actively mitotic and undifferentiated and have a long mitotic future.
d. actively mitotic and undifferentiated and have a long mitotic future.
The Correct Answer and Explanation is :
Correct Answer:
d. actively mitotic and undifferentiated and have a long mitotic future.
Explanation:
The Law of Bergonié and Tribondeau, formulated in 1906, describes how cells respond to ionizing radiation. This law states that the radiosensitivity of a cell is directly proportional to its reproductive activity and inversely proportional to its level of differentiation. In simpler terms, cells that divide rapidly and remain undifferentiated are more susceptible to radiation damage.
Key Principles of the Law:
- Cells that are highly mitotic (actively dividing) are more radiosensitive because radiation causes damage during cell division. When DNA is damaged in these rapidly dividing cells, errors accumulate, leading to cell death.
- Cells that are undifferentiated (stem-like or progenitor cells) are more radiosensitive because they lack specialized functions and are in a continuous cycle of division. Differentiated cells, such as neurons or muscle cells, divide less frequently and are more radioresistant.
- Cells with a long mitotic future (progenitor or stem cells) are more radiosensitive because they have many future divisions where radiation-induced damage can be propagated.
Examples of Radiosensitive Cells:
- Hematopoietic stem cells (found in bone marrow)
- Basal cells of the epidermis
- Germ cells (sperm and egg precursors)
- Gastrointestinal epithelial cells
In contrast, mature nerve cells, muscle cells, and other highly differentiated cells are more radioresistant because they rarely divide.
Clinical Relevance:
This principle is important in radiotherapy for cancer treatment. Since cancer cells are often rapidly dividing and undifferentiated, they are more sensitive to radiation. However, normal tissues containing stem cells, like the bone marrow and intestinal lining, can also be affected, leading to side effects like anemia, nausea, and immune suppression.
Thus, actively mitotic, undifferentiated cells with a long mitotic future are most sensitive to ionizing radiation, making option d the correct answer.