Lateral mesoderm

Lateral mesoderm is one of the three primary divisions of the embryonic mesoderm, the other two being the paraxial mesoderm and the intermediate mesoderm. The lateral mesoderm is the most peripheral layer, located adjacent to the ectoderm and endoderm in the developing embryo.

Formation

The lateral mesoderm forms during the process of gastrulation, when cells from the epiblast layer migrate through the primitive streak to form the mesoderm. The cells that migrate to the most lateral position form the lateral mesoderm.

Divisions

The lateral mesoderm further divides into two layers: the somatic or parietal mesoderm, and the splanchnic or visceral mesoderm. The space between these two layers forms the intraembryonic coelom, which gives rise to the body cavities.

Somatic Mesoderm

The somatic mesoderm lines the inside of the embryonic ectoderm and forms the body wall and the extraembryonic mesoderm of the amnion and chorion. It also contributes to the formation of the limb buds.

Splanchnic Mesoderm

The splanchnic mesoderm lines the outside of the embryonic endoderm and forms the wall of the gut tube. It also contributes to the formation of the heart, blood vessels, and blood cells.

Derivatives

The lateral mesoderm gives rise to several important structures in the adult body. These include the serous membranes lining the body cavities, the circulatory system, the walls of the gut, and the muscles and connective tissues of the limbs.

See also

• Mesoderm
• Gastrulation
• Embryogenesis