____ retards phagocytotic activities of WBCs.

Options

A. Corstisol
B. Epinephrine
C. Estrogen
D. Thymosin

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:** The question asks which substance retards (or slows down) the phagocytic activities of white blood cells (WBCs). Phagocytosis is a process where WBCs engulf and digest pathogens or debris.

2. **Identifying WBCs Role:** White blood cells are crucial components of the immune system. Their primary function is to protect the body against infections and foreign invaders.

3. **Hormonal Influence on WBCs:** Certain hormones can affect the immune response. In this context, we need to identify which hormone specifically suppresses or retards the activity of WBCs.

4. **Exploring Adrenal Gland Functions:** The adrenal glands, located on top of each kidney, produce various hormones. They consist of two main parts: the adrenal cortex and the adrenal medulla.

5. **Focusing on the Adrenal Cortex:** The adrenal cortex has three layers: zona glomerulosa, zona fasciculata, and zona reticularis. Each layer produces different hormones.

6. **Identifying Relevant Hormones:** The zona fasciculata produces glucocorticoids, the most notable of which is cortisol. Cortisol is known for its anti-inflammatory properties and its ability to suppress the immune system.

7. **Conclusion:** Based on the information, cortisol is the hormone that retards the phagocytic activities of WBCs. Therefore, the answer to the question is cortisol.

**Final Answer:** Cortisol retards phagocytic activities of WBCs.

---