Yolk Sac

The yolk sac is a part of the developing embryo in animals, including humans. It is a membrane-bound organ from which an embryo derives its nutrition until its digestive system is developed and functional. The yolk sac is composed of a number of components, including a central fluid-filled cavity, a yolk plug, yolk diverticula and extraembryonic mesoderm. It is a key organ in early embryonic development, as it is responsible for providing nutritional support until the digestive system of the embryo is functional. In humans, the yolk sac is visible and can be detected in ultrasound scans as early as five weeks. The yolk sac is a vital structure in the development of any mammal and is essential to the growth and survival of the embryo.