This protein, called ovocleidin-17 (OC-17), is only found in chicken ovaries. Scientists argue that chickens must have come first because OC-17 is essential for forming eggshells, which are built ...

Chicken yolks, or ova, form in the chicken's ovaries. A fully formed ovum will leave the ovary and be deposited into the oviduct. This part of the chicken's reproductive system has five distinct ...