mesodermu

Mesodermu, commonly called the mesoderm, is the middle germ layer of the trilaminar embryo formed during gastrulation. It arises as cells from the epiblast migrate between the ectoderm and endoderm and organize into regional populations: axial, paraxial, intermediate, and lateral plate mesoderm. The axial mesoderm contributes to the notochord, while the paraxial, intermediate, and lateral plate regions give rise to most musculoskeletal, urogenital, and circulatory tissues.

Derivatives of mesoderm include the musculoskeletal system (bone, cartilage, skeletal muscle), the dermis, and the cardiovascular system (heart, blood vessels, blood cells). The kidneys and gonads develop from intermediate mesoderm and adjacent tissues, while the lining of body cavities—the serous membranes—is formed by coelomic (mesothelial) cells from lateral plate mesoderm. Limb buds and body-wall structures mainly arise from lateral plate mesoderm, whereas vertebrae and associated back muscles derive largely from somites formed by paraxial mesoderm.

Extraembryonic mesoderm lines the amnion and yolk sac and contributes to the formation of fetal membranes and early circulatory structures. In the mature organism, mesoderm-derived tissues differentiate into connective tissues throughout the body and contribute components of the endocrine and immune systems. Proper mesoderm development is essential for the formation of most internal organs and structural support.