During gastrulation,$.......$ is formed.

$A$ temporary endocrine gland in the human body is

During embryonic development,which germ layer gives rise to the endoskeleton and muscles?

The type of placenta found in human beings is of type

The vascular system and excretory organs are developed from which germ layer?

$A$: If fertilization occurs,the corpus luteum is rescued from regression by human chorionic gonadotropin $(hCG)$,which is produced by the placenta.
$R$: In the first trimester,the corpus luteum,stimulated by $hCG$,is responsible for the production of progesterone.