Question

Signals from a fully developed fetus and placenta ultimately lead to parturition which requires the release of?

• A. Oxytocin from foetal pituitary
• B. Oxytocin from the maternal pituitary
• C. Relaxin from the placenta
• D. Estrogen from placenta

Answer 1

The correct option is B

Oxytocin from the maternal pituitary

The correct option is B:

Explanation for the correct option:

Option B:

1. Oxytocin is also called the birth hormone.
2. Oxytocin is released from the maternal pituitary which stimulates the contraction of the uterine muscles.

Explanation for the incorrect options:

Option A:

Oxytocin is released from the maternal pituitary and not from the fetal pituitary.

Option C:

1. Relaxin secreted by the placenta increases the flexibility of the pubic symphysis.
2. It also dilates the uterine cervix during labor.

Option D:

1. Estrogen is released from the placenta during parturition.
2. It nullifies the effect of progesterone that maintains pregnancy.
3. It also makes the uterine muscles sensitive to oxytocin.
4. It also causes the fetal anterior pituitary to secrete ACTH(adrenocorticotropic hormone).

Final answer: Signals from a fully developed fetus and placenta ultimately lead to parturition which requires the release of oxytocin from the maternal pituitary.