Question

Explain the process of formation of placenta in a human female after the implantation of the blastocyst in the endometrium of the uterus.

Hint:

Placenta forms from chorionic villi and maternal tissue post-implantation; it supports foetal development and hormone secretion.

Answer 1

Step 1: After implantation, the finger-like projections called chorionic villi develop from the trophoblast (outer layer of the blastocyst) into the surrounding uterine tissue.
Step 2: These villi grow into the maternal tissue and are surrounded by blood spaces called lacunae formed in the endometrium.
Step 3: The chorionic villi and uterine tissue together form a structural and functional unit called the placenta.
Step 4: Placenta acts as a nutritive, respiratory, excretory, and endocrine organ. It facilitates the exchange of oxygen, nutrients, and waste between mother and foetus.