ANATOMY

Detailed explanation-1: -A chick emerges from a fertile egg after twenty-one days of incubation. The germinal disc is visible on the surface of the yolk. The development of the chick begins in the single cell formed by the union of two parental cells, egg and sperm, in the process known as fertilization.

Detailed explanation-2: -Chicks will typically hatch at day 21. If the fertilized eggs were cooled prior to incubation, the process might take a little longer. If you are at day 21 with no hatch, give the eggs a few more days.