Question

Signals for parturition originate from

• A. oxytocin released from maternal pituitary
• B. both placenta as well as a fully developed foetus
• C. the fully developed foetus only
• D. placenta only

Answer 1

The correct option is B

both placenta as well as a fully developed foetus

The correct option is B.

Explanation of correct option:

1. The foetus when fully developed signals that it has matured by secreting certain hormones.
2. The hormones diffuse through the placenta into the mother's blood and cause the release of oxytocin that causes uterine contractions.
3. These signals are called foetal ejection reflexes.
4. These contractions are induced by both placental and foetal hormones.
5. These hormones are estrogen, oxytocin, relaxin, prostaglandins, and corticotropin-releasing hormone.

Explanation of incorrect options:

Option A:

1. Oxytocin is called the birth hormone.
2. During childbirth, it causes contraction of the uterine muscles for easy delivery of the foetus.

Option C:

The fully developed foetus signals its maturation by secreting certain hormones. However, signals for parturition develop both from the foetus as well as from the placenta.

Option D:

1. The hormones secreted by the foetus diffuse through the placenta to the mother's blood.
2. The placenta along with the foetus secretes hormones that signal parturition.

Final answer: Signals for parturition originate from both placenta as well as a fully developed foetus.