development of the embryo chicken.

allantoic allantois amnion anatomy animal biology black blastocoel blastoderm body candling cardiac cavity chick chicken chorion chorionic circle circulatory column cord day development domesticus education egg eggs embryo embryonic epiblast evolution fertilization fetus first gallus growing growth heart hours hypoblast incubator inside life light microscope microscopical natural optical organs pipping prenatal red research sac shape sperm stages structure system tissue tooth twenty umbilical vein veins vertebrae vesicle yolk