After implantation of the blastocyst the embryonic cells divide further. At the end of week 2, three germ layers are formed. The mesoderm is the middle of the three germ layers of the early embryo: ectoderm – mesoderm – endoderm. This layer gives rise to smooth and striated muscle, the skeleton with cartilage, connective and adipose tissue, dentine of teeth, circulatory and lymphatic systems and much more (Hill, 2020).