Yolk

**Yolk** is a cellular organ or small body that is formed in the egg cell of various species of animals and plants, as well as in the primary egg cells of fish. In this organ, the development and differentiation of primary germ cells occurs before fertilization. It is in the yolk that everything that is fertilized by the fertilized egg is located - the earliest cells of the embryonic development of the future organism.

The yolk is the content of sex chromosomes in the cell body