Question

Describe in brief the changes that the uterus undergoes to receive the zygote and if zygote is not formed.

Answer 1

(i) On receiving the zygote the uterine walls becomes thicker and if the zygote gets implanted in the into the uterus then the female becomes pregnant. The embryonic development of the zygote starts immediately. The embryo moves down into the uterus forming a thick and soft lining of blood vessels around itself. After implantation, placenta which is a special tissue, develops between the uterine wall and the embryo.

ii) In case the egg is not fertilised, the blood lining breaks as it is not needed anymore and exits the body in the form of blood and mucous via the vagina. This is known as menstruation. It occurs 14 days after ovulation.