Q. Signals from fully developed foetus and placenta ultimately lead to parturition, which requires the release of :
(a) Oxytocin from maternal pituitary.
(b) Oxytocin from foetal pituitary.
(c) Relaxin from placenta.
(d) Estrogen from placenta.
Solution :
Correct option : A The process of giving birth to a baby is called parturition. It starts with a rise in oestrogen/progesterone ratio, increase in level of oxytocin secretion by the mother. Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully developed foetus and the placenta, which induces mild uterine contractions called foetal ejection reflex. This reflex triggers the release of oxytocin from the maternal pituitary. This hormone acts on uterine muscle and causes more contractions, which in turn secrete more oxytocin .The stimulatory reflex between the uterine contraction and oxytocin secretion continues resulting in stronger and stronger contractions which leads to expulsion of the baby. So, the correct answer is ‘Oxytocin from maternal pituitary’
