Yolk Sac

Yolk sac

The yolk sac is a pocket-like outgrowth of the digestive tract in the embryos of some vertebrates, surrounding the yolk. The yolk sac performs an important function in providing nutrition to the developing embryo - it digests the yolk, making it available to the whole body.

In birds and reptiles, the yolk sac forms early in embryonic development from the midgut and connects to the yolk sac through the vitelline duct. As the embryo develops, the yolk sac decreases in size and eventually disappears.

Mammals do not have a yolk sac because their embryos develop in the uterus and receive nutrition from the mother's body through the placenta. But in marsupials, at the beginning of intrauterine development, the function of the yolk sac is performed by the so-called marsupial sac.

Thus, the yolk sac plays a key role in providing nutrition and normal development of embryos in birds, reptiles and some other animals.

The yolk sac is an organ that is formed in the embryo during intrauterine development. It performs an important function in the development of the fetus and provides it with essential nutrients.

The yolk sac is a sac that is located in the abdominal cavity of the fetus. It consists of two layers: the outer layer, called the vitelline layer, and the inner layer, called the vitelline vesicle. The yolk sac contains the yolk, which is a source of nutrients for the fetus during its development.

The formation of the yolk sac occurs 16-18 days after conception. During this period, the yolk sac divides into two parts: the inner yolk sac and the outer yolk sac. The inner yolk sac remains connected to the yolk sac, and the outer yolk sac begins to separate from the yolk sac.

Functions of the yolk sac:

1. Providing nutrients to the fetus. The yolk sac contains a large amount of nutrients such as proteins, fats, carbohydrates and vitamins. These substances are necessary for the normal development of the fetus.
2. Participation in the formation of the placenta. The yolk sac is involved in the formation of the placenta, a special organ that connects the fetus to the mother’s body.
3. Participation in the development of the immune system. The yolk sac plays an important role in the formation of the fetal immune system. This occurs due to the presence of lymphocytes in the yolk sac, which are involved in protecting the body from infections.
4. Role in lung development. The yolk sac also plays an important role in fetal lung development. This is due to the presence in the yolk sac of a large amount of surfactant, a substance that ensures the normal functioning of the lungs.
5. Participation in metabolism. The yolk sac is involved in the metabolism between the fetus and the mother's body, which allows the fetus to receive necessary nutrients and remove metabolic waste products.

Currently, scientists are increasingly beginning to understand the importance of the yolk sac for embryology and genetics. This organ has been known since ancient times. In ancient times, the Greeks called it "viscera" or "pancreas" and also used it in food to add flavor and sweetness.

Description of the yolk sac The yolk sac is one of the most significant organs in the embryo