Question

Which of the following sentences is true for the chorion?
A. The organ in the uterus connected to the fetus by the umbilical cord
B. The sac or pouch-like organ within uterus containing the amniotic fluid surrounding the fetus
C. A membrane developing around an embryo, contributing to the formation of the placenta
D. None of the above

Answer 1

Hint:
In mammals (except marsupials), the chorion develops a dense network of blood vessels and forms a close relationship with the endometrium (lining) of the female uterus. Chorion and endometrium combine to form the placenta, which is the embryo's primary organ of respiration, nutrition, and excretion.

Complete answer:
The chorion is involved in the formation of the placenta. The chorionic villi on the trophoblast and uterine tissue interdigitate to form the placenta, which connects the developing embryo to the mother's body. The chorionic plate of the placenta is formed by cytotrophoblast proliferation and degeneration with fibrin-type fibrinoid deposition. Fetal allantois vessels fuse with this layer and connect to vessels formed independently within villi. The placental membrane is the site where the mother and fetus exchange gasses, nutrients, and other substances. The membrane is formed by the syncytiotrophoblast, cytotrophoblast, embryonic connective tissue (Wharton's jelly), and fetal blood vessel endothelium.
So, the correct answer is:- A membrane developing around an embryo, contributing to the formation of the placenta

Option ‘C’ is correct

Note:
The placenta is made up of both maternal tissue and embryonic tissue. The chorion is the placenta's embryonic component. It is made up of fetal blood vessels and trophoblasts that form finger-like structures called chorionic villi. The chorion is one of the membranes that surround the fetus. The chorion facilitates the exchange of nutrients, gasses, and wastes between the embryo and the body of the mother. The placenta is made up of the outermost embryonic membrane.