The vitelline duct, also known as the yolk stalk, is a structure that connects the developing embryo to the yolk sac during early embryonic development. This duct plays a crucial role in nutrient transfer, allowing the embryo to absorb essential substances from the yolk sac, which provides nourishment before the placenta forms. As development progresses, the vitelline duct typically regresses and eventually disappears. In some cases, remnants of the duct can persist, leading to conditions such as Meckel's diverticulum, which is a small pouch that can form in the intestine. Understanding the vitelline duct is important in embryology and developmental biology.