Extraembryonic membranes are also called
a)	Foetal membranes	b)	Embryonic membranes
c)	Outer membranes	d)	Inner membranes

(a)

Extra embryonic membrane are also called foetal membrane.

Extraembryonic or Foetal Membranes

The growing embryo/foetus develops four membranes called the extraembryoic or foetal membranes. These include chorion, aminion, allantois and yolk sac

(i) Chorion It is made up of trophoblast outside and somatopleuric extraembryonic mesoderm inside. It completely surrounds the embryo and protects it. It also takes part in the formation of placenta

(ii) Amnion It is composed of trophoblast inside and somatopleuric extraembryonic mesoderm outside. The space between the embryo and the amnion is called the amniotic cavity, which is filled with a clear, watery fluid secreted by both the embryo and the membrane. The amniotic fluid prevents dessication of the embryo and acts as a protective cushion that absorbs shocks

(iii) Allantois The allantois is composed of endoderm inside and splanchnopleuric extraembryoic mesoderm outside. It is a sac like structure, which arises from the gut of the embryo near the yolk sac. In human the allantois is small and non-functional except for furnishing blood vessels to the placenta

(iv) Yolk Sac The primary yolk sac consists of endoderm inside and splanchnopleuric extraembryoic mesoderm outside. The yolk sac is non-functional in human beings except that it functions as the site of early blood cell formation