The function of the allantois in mammals is:

The foetal membrane which is the source of the first blood corpuscles to enter the circulation of the embryo is called:

$A$: If both the ovaries are removed after the first trimester of pregnancy,still there would be normal growth of the foetus.
$R$: After the first trimester,the placenta secretes sufficient progesterone.

Which of the following is not a correct statement about the umbilical cord?

What is seen in the zygote during embryogenesis?

Which one of the following statements with regard to embryonic development in humans is correct?