What is the function of the increased levels of estrogen,progesterone,cortisol,prolactin,and thyroxine in the maternal blood during pregnancy?

Which cavity arises by the invagination of endoderm and mesoderm?

$A$: Human chorionic gonadotrophin $(hCG)$ prevents the corpus luteum from involuting.
$R$: It has properties similar to luteinizing hormone $(LH)$.

Given below are two statements with respect to gastrulation.
$Statement-I$: Root of amniotic cavity is lined by amniogenic cells, which divides to form chorion.
$Statement-II$: Chorion is an embryonic membrane that participates in development of the embryo.
Choose the most appropriate answer from the options given below.

The fluid filled in the blastocoel cavity of blastula is

The type of placenta in humans is: