... feature of embryo:The heart of embryonic disk begins to jump,the blood vessel of yolk sac appears, and blood circulate ... growth feature of embryo:the eyeball becomes black,the embryo starts to grow.6,Hatching days :chicken\6days ,duck\7days ,goose ... allantois protrude towards the capitulum ,enterocoelia closed and the cartilage starts to ossify.8,Hatching days:chicken \10days ,duck\12-13days ...