Question

Foetal ejection reflex in human female is induced by
(a)Release of Oxytocin from the pituitary
(b)Pressure exerted by amniotic fluid
(c)Differentiation of mammary glands
(d)Fully developed fetus and placenta

Answer 1

Hint: The mild uterine contraction in response to stimuli during parturition is called fetal ejection reflex. It is the major cue behind the process of parturition.

Complete answer:
Fetal ejection reflex in human females is induced by the fully developed fetus and placenta. It is the major cue which moves the baby from the uterus and into the birth canal initially. This reflex further triggers the release of oxytocin from the maternal posterior pituitary due to increased firing in the hypothalamo-hypophyseal tract. The hormone, Oxytocin then induces stronger uterine contractions which further increases the pressure on the cervix which finally leads to the expulsion of the baby from the birth canal. The pressure keeps on increasing until the baby is expelled out. The phenomenon of expelling the fully-grown fetus from the mother’s uterus is called Parturition. Fetal ejection reflex is a neuroendocrine mechanism since it involves hormonal actions. It is also called the Ferguson reflex. This mechanism is characteristic of mammals.

Additional Information: Oxytocin targets receptors present on the myometrium that is upregulated by a functional increase of the estrogen-progesterone ratio mediated by a decrease in myometrial sensitivity to progesterone, due to a decrease in progesterone receptor A, and a concurrent increase in myometrial sensitivity to estrogen, due to an increase in estrogen receptor α, causing myometrial contractions.
Mammary glands undergo differentiation and also start producing milk at the later stages of the pregnancy. This phenomenon is called lactation.
Amniotic fluid is the clear liquid that surrounds a developing fetus in a mother’s womb. It is primarily formed from the mother’s plasma. Amniotic fluid cushions the baby from external blows and provides homeostatic conditions.
So, the correct answer is ‘Fully developed fetus and placenta’.

Note: - Niles Newton was the first to use the term fetal ejection reflex in the 1960s.
- Oxytocin targets receptors present on the myometrium that is upregulated by a functional increase of the estrogen-progesterone ratio mediated by a decrease in myometrial sensitivity to progesterone, due to a decrease in progesterone receptor A, and a concurrent increase in myometrial sensitivity to estrogen, due to an increase in estrogen receptor α, causing myometrial contractions.