Question

Placenta is the structure formed

• A. By fusion of germ layers
• B. By foetus only
• C. By the union of foetal and uterine tissue
• D. By uterus only

Answer 1

Answer: (C)

By the union of foetal and uterine tissue

The placenta is a disc-like special tissue which is composed of both maternal tissue and tissue derived from the embryo. It acts as a fetomaternal organ with two components- foetal placenta (chorion) which develops from the same blastocyst that forms the fetal and maternal placenta that forms the maternal tissue. The chorion is composed of fetal blood vessels and trophoblast which are organized into finger-like structures called chorionic villi. The chorionic villi come to lie in uterine lacunae that contain blood. The cells forming the wall of chorionic villi bear microvilli which increase their surface area for quick and adequate exchange of materials by diffusion and active transport.

Thus, the correct answer is option C.