How do different cell types work

Cell differentiation

All cells of multicellular organisms emerge from the zygote, which is the result of the fusion of the egg cell and sperm. From this one cell all different specialized cells emerge in the course of development. One speaks here of cell differentiation.

After the egg cell and sperm have merged, the zygote divides several times. This cluster of cells is called the morula. This continues until a hollow ball is formed that is filled with liquid. This stage of embryonic development is called the blastula. The subsequent gastrulation (invagination) leads to the formation of the three cotyledons, from which various types of tissue develop in later stages: The ectoderm is on the outside, from which the skin and the nervous system emerge in the course of further development. The mesoderm lies in the middle of the gastrula; it later forms the connective tissue, muscles and bones. Inside is the endoderm, from which the digestive system and other important glands later emerge.

The primordial germ cell, i.e. the zygote, has the property of being able to differentiate into a complete organism. This is known as totipotent. In the first stages of development, i.e. the blastocyst stage, the cells are called pluripotent. This means that the cells, which are also called embryonic stem cells, can still develop in all different tissues, but not in an entire organism. In the further course, the stem cells also lose this property and become multipotent. Only certain tissues can be made from them. This is also referred to as adult stem cells, which are responsible for the regeneration of skin or liver cells in humans, for example.