The hormone used to prevent abortion is .....

Placenta acts as an endocrine tissue and produces several hormones like:
$A.$ Human chorionic gonadotropin $(hCG)$
$B.$ Human placental lactogen $(hPL)$
$C.$ Estrogens
$D.$ Progesterone

Apart from endocrine function,what are the other functions of the placenta?

The best definition of the process of gastrulation is that it is a process where the

$A$: 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.

The pattern of cleavage in an egg is determined by which of the following?