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 through interaction of chorionic villi and uterine tissues, serving as a nutritive, respiratory, excretory, and endocrine organ for the embryo.

Answer 1

Step 1: After implantation, finger-like projections called chorionic villi appear on the trophoblast part of the blastocyst. Step 2: The uterine tissue and maternal blood vessels surround these villi. Step 3: Chorionic villi and uterine tissue combine to form the placenta. Step 4: The placenta facilitates the exchange of nutrients, gases, and wastes between the mother and the embryo and acts as an endocrine tissue by secreting hormones like hCG, progesterone, and estrogens.