Which type of placenta is present in the early human embryo?

Identify the correct labeling and its function from the given diagram of a developing fetus.

The first sign of the growing foetus may be noticed by listening to the heart sound carefully through the stethoscope. The embryo's heart is formed . . . . . . .

An avian blastula is called

The animals in which the complete embryo develops inside the mother's body through a placenta are known as:

After fertilization, the corpus luteum remains in a woman for about: (in $days$)