The development of a human being can be divided into several stages from fertilisation to birth and from birth to old age. Development depends on genetic and epigenetic factors, and is carried out by a combination of cellular and molecular mechanisms that result in the formation of tissues (histogenesis) and shape organs and the human being as a whole (morphogenesis). During embryonic development, a structure with two cell layers (bilaminar embryo) is produced. Cells from the dorsal layer (epiblast) of this embryo migrate and a trilaminar embryo is produced with the three germinative layers: ectoderm, mesoderm and endoderm. In addition, the ectoderm forms the neural tube and neural crests, whose cells migrate through the mesoderm and form many cells and tissues of the organism. Finally, you will see that each germinative leaf can generate different human tissues and organs.