Question

a. Define parturition. Name the hormones involved in the induction of Parturition.
b. In our society women are often blamed for giving birth to daughters. Can you explain why this not correct?

Answer 1

a. Vigorous contraction of the uterus at the end of pregnancy causes expulsion or delivery of the foetus. This process of delivery of the foetus (childbirth) is called parturition. It is induced by a complex neuroendocrine mechanism.

Hormones involved in the induction of parturition are oxytocin and relaxin.

The signals for parturition originate from the fully developed foetus and the placenta which induce mild uterine contractions called foetal ejection reflex. This triggers release of oxytocin from the maternal pituitary. Oxytocin acts on the uterine muscle and causes stronger uterine contractions, which in turn stimulates further secretion of oxytocin. The stimulatory reflex between the uterine contraction and oxytocin secretion continues resulting in stronger and stronger contractions. This leads to expulsion of baby out of the uterus through the birth canal – parturition.

Relaxin facilitates parturition by softening the connective tissue of pubic symphysis.

b. In our society women are often blamed for giving birth to daughters. But it is not correct. The chromosome pattern in human female is XX and that in the male is XY. Therefore, all the haploid gametes produced by the female (ova) have the sex chromosome X, whereas in the male gametes (sperms) the sex chromosome could be either X or Y. Hence 50% of sperms carry X chromosomes while the other 50% carry the Y. After fusion of the male and female gametes, the zygote would carry either XX or XY depending on whether the sperms carrying X or Y has fertilized the ovum. The zygote carrying XX would develop into a female and XY form a male. So, the sex of the baby is determined by father and not by the mother.