Prolactin activates

Options

A. Growth of breasts and secretion of milk in mammary glands
B. Secondary sexual characters in males
C. Melatonin secretion
D. Estrogen secretion

Answer

To answer the question "Prolactin activates," we need to analyze the options provided and understand the role of prolactin in the body.

### Step-by-Step Solution:

1. **Understanding Prolactin**: Prolactin is a hormone produced by the anterior pituitary gland. It plays a crucial role in the reproductive system, particularly in females.

2. **Function of Prolactin**: The primary functions of prolactin include:
- Stimulating the growth and development of mammary glands (the glands responsible for milk production).
- Promoting the secretion of milk from these glands after childbirth.

3. **Evaluating the Options**:
- **Option 1**: Growth of breasts and secretion of milk in mammary glands.
- This option is correct as prolactin is directly involved in both the development of mammary glands and the secretion of milk.
- **Option 2**: Secondary sexual characters in males.
- This option is incorrect. The secondary sexual characteristics in males are primarily regulated by testosterone, not prolactin.
- **Option 3**: Melatonin secretion.
- This option is incorrect. Melatonin is secreted by the pineal gland and is not influenced by prolactin.
- **Option 4**: Estrogen secretion.
- This option is incorrect. Estrogen is primarily regulated by gonadotropins like luteinizing hormone (LH) and follicle-stimulating hormone (FSH), not by prolactin.

4. **Conclusion**: The correct answer is that prolactin activates the growth of breasts and secretion of milk in mammary glands.

### Final Answer:
**Prolactin activates the growth of breasts and secretion of milk in mammary glands.**

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