Fertilization and Early Embryonic Development

Free Response

What do you think would happen if multiple sperm fused with one egg?

Hint:

Multiple sperm can fuse with the egg, resulting in polyspermy. The resulting embryo is not genetically viable and dies within a few days.

Why do mammalian eggs have a small concentration of yolk, while bird and reptile eggs have a large concentration of yolk?

Hint:

Mammalian eggs do not need a lot of yolk because the developing fetus obtains nutrients from the mother. Other species, in which the fetus develops outside of the mother’s body, such as occurs with birds, require a lot of yolk in the egg to nourish the embryo during development.