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Which type of placenta is formed of chorion and allantois and found in Parameles and Dasyurus?

Option: 1

Chorio-vitelline placenta

Option: 2

 Chorio-allantoic placenta

Option: 3

 Chorionic placenta

Option: 4

Both A and C

Answers (1)


Chorio-allantoic placenta is formed when the yolk sac remains undeveloped, and the fusion found between the uterine wall and the embryo is lined by chorion and allantois. Since the placenta is formed of chorion and allantois, it is termed as chorio-allantoic placenta. This type of placenta is found in Parameles and Dasyurus. On the other hand, the chorio-vitelline placenta is a primitive type of placenta found in some marsupials like opossum and kangaroo, where the yolk sac becomes very huge and combines broadly with the chorion. The chorionic placenta is formed of a thickened layer of chorion containing sinuses filled with maternal blood and is found in human beings. Therefore, options A and C are incorrect.

Hence, option b is the correct answer.

Posted by

Anam Khan

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