Question

he number of fetal membranes in humans is
A. 1
B. 3
C. 4
D. 0

Answer 1

Hint:- During the development of the fetus, some membranes remain associated with it. These membranes are called fetal membranes. Fetal membranes are thin tissues surrounding the fetus during gestation. These membranes are very crucial for maintaining pregnancy upto delivery as well as the protection and health of the growing fetus.

Complete answer:
Step 1: Let us first know the fetal membranes in humans-
Amnion- Embryo when first formed is closely covered by a membrane called amnion. Amniotic fluid fills the amnion causing the amnion to expand as a result of which amniotic sac is formed.
Chorion- It is a membrane surrounding amnion, embryo and other membranes. It is the outermost fetal membrane surrounding the embryo and is present in amniotes (reptiles, birds and mammals). Development of chorion takes place from the outer fold on the surface of the yolk sac, lying outside the zona pellucida in animals, which are known as vitelline membrane in other animals.
Allantois- It is a hollow sac-like structure which is filled with a clear fluid forming part of a developing amniote’s conceptus. It facilitates the exchange of gases and handles liquid waste.
Yolk sac- This is also known as the umbilical vesicle and is formed by cells of the hypoblast adjacent to the embryonic disc. It is a membranous sac which is attached to the embryo and is important for blood supply in the early embryonic stage.

Step 2: Based on the above discussion, it is clear that the correct answer is (C)- 4.

Note:- Amniotic fluid surrounding and protecting the baby during pregnancy constitutes fetal cells and various proteins. Small amount of this fluid is sampled from the amniotic sac and used mainly in prenatal diagnosis for chromosomal abnormality or other defects as well as for sex determination in a medical procedure called amniocentesis.