Which one the following hormone stimulates the secretion of milk form the mother's breasts when the baby is sucking ?

Options

A. Progesterone
B. Oxytocin
C. Prolactin
D. Relaxin

Answer

To solve the question of which hormone stimulates the secretion of milk from the mother's breasts when the baby is sucking, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Hormones Listed**: The question provides four options: Progesterone, Oxytocin, Prolactin, and Relaxin. We need to evaluate each hormone's role in milk secretion.

2. **Evaluate Progesterone**:
- **Source**: Progesterone is produced by the corpus luteum in the ovaries.
- **Function**: Its primary role is to support pregnancy and prepare the mammary glands for milk production.
- **Conclusion**: Progesterone does not stimulate milk secretion; it is involved in the formation of alveoli in the mammary glands. **(Not the correct answer)**

3. **Evaluate Oxytocin**:
- **Source**: Oxytocin is produced by the hypothalamus and released by the posterior pituitary gland.
- **Function**: It causes contraction of smooth muscles and is responsible for the ejection of milk during breastfeeding (let-down reflex).
- **Conclusion**: Oxytocin is indeed responsible for stimulating milk secretion when the baby suckles. **(Correct answer)**

4. **Evaluate Prolactin**:
- **Source**: Prolactin is produced by the anterior pituitary gland.
- **Function**: It is primarily responsible for the production of milk in the mammary glands.
- **Conclusion**: While prolactin is crucial for milk production, it does not stimulate the ejection of milk. **(Not the correct answer)**

5. **Evaluate Relaxin**:
- **Source**: Relaxin is secreted by the ovaries during pregnancy.
- **Function**: It helps to relax the pelvic ligaments and prepare the body for childbirth.
- **Conclusion**: Relaxin has no role in milk secretion. **(Not the correct answer)**

6. **Final Conclusion**: Based on the evaluations, the hormone that stimulates the secretion of milk from the mother's breasts when the baby is sucking is **Oxytocin**.

### Answer:
**Oxytocin**