Definition
The vitelline sac is essentially another term for the yolk sac, referring to the membrane-bound structure that surrounds the yolk and provides nutrients to the developing embryo. It's like a food delivery service ๐ for the developing embryo. Nutrients, hormones, and growth factors are transported from the yolk to the growing embryo. 'Vitelline' emphasizes the yolk component, while 'sac' describes the pouch-like structure.