Answer:
The egg yolk of a chicken corresponds to the female's oocyte II, which would become a chick if fertilized by a male gamete. The yolk have the nutrients that provide the energy for embryo development. In the case of humans and other animals called eutheries or placentals, embryos are fed through an organ called placenta, which connects the embryonic organism with mother's organism. Thus, there is no need for a type of "yolk" to provide the embryo with energy, as is the case with chickens and other animal species in which embryonic development occurs without direct attachment to the maternal organism.
