Question

During the reproductive cycle of a human female, when, where and how does a placenta develop? What is the function of placenta during pregnancy and embryo development?

Answer 1

During the reproductive cycle of human female, placenta develops after the implantation of zygote in the uterus.

Firstly, the trophoblast cells of blastocyst absorb food and oxygen from the increasingly vascularised uterine lining. The allantois grows out from the embryo and fuses with the chorion to form the allantochorion that develops into placenta.

 

The functions of placenta are as follows:

 

Placenta is the circular organ present in the uterus of pregnant mammals that is required for the nourishment and maintenance of the foetus. It performs various function like:
1) Nutrition : It helps to transport nutrients from mother's blood to foetus for its development.

2) Respiration: It provides oxygen to the foetus and take CO₂ away from the foetus.

3) Excretion: It helps in the removal of waste products from the foetus and transfers them to mother's blood.

4) Immunity: It provides immunity to the foetus. Antibodies developed in mother's blood passes onto the foetus through the placenta.

5) Storage: It stores some fats, glycogen and iron.

6) Secretion of hormones: It secretes many hormones like oestrogen, progesterone, gonadotropin and placental lactogen.