Question

Which of the following is regarded as the 'urinary bladder of embryo'?
(a) Amnion
(b) Allantois
(c) Chorion
(d) Yolk sac

Answer 1

Hint: An embryo is the early development stage of an animal when it is in the egg or within the uterus of the mother. During conception, it is the unborn child which is at the end of the 7th week. It is created by the first mitotic division when the fertilization of a human takes place.

Complete answer:
The allantois is regarded as the 'urinary bladder of embryo'. It is a sac-like structure that is hollow. Clear fluid is present inside it which helps in the formation of the part of a developing amniote's conceptus. This consists of the extraembryonic tissues and all embryonic tissues in it which helps in the exchange of the gases for the embryo and manages liquid waste. It provides nutrition to the embryo and helps in excretion. It consists of several blood vessels in eighth and allows the liquid waste from the embryo along with the exchange of gases. The axis for the development of the umbilical cord is done by allantois.

Additional information:
Amnion: It is a membrane that forms the outer lining of the embryo and is filled with amniotic fluid in it which causes the amnion to expand for the formation of an amniotic sac that helps in providing a protective environment for the developing embryo or foetus.
Chorion: It is known as the outermost layer of the foetus around the embryo which develops from an outer fold on the surface of the yolk sac which is present outside the zona pellucida and is defined as a vitelline membrane.
Yolk Sac: It is a membrane that is attached to an embryo for the formation of the cells of the hypoblast along with the embryonic disc which is known as the umbilical vesicle.

So, the correct answer is 'Allantois'.

Note:
The lower animals get their nutrition for the embryo from the yolk. The quality of an embryo is determined by the rhythm of its division in the first days and its appearance of the cells. The early stages of an embryo in humans is structurally similar to the fish.