Paraxial mesoderm

Paraxial Mesoderm

The Paraxial mesoderm is a type of mesoderm, one of the three primary germ layers in the very early embryo. The mesoderm is the middle layer of cells or tissues of an embryo, or the part from which the musculoskeletal, circulatory, and genitourinary systems develop. The paraxial mesoderm is located along the sides of the neural tube and is arranged into a series of blocks known as somites.

Formation

The paraxial mesoderm forms during the third week of human embryogenesis. It arises from the primitive streak, a structure that forms in the blastula during the early stages of embryonic development. The cells of the paraxial mesoderm migrate laterally and cranially from the primitive streak to form a thickened plate of mesoderm on either side of the midline.

Somitogenesis

The process by which the paraxial mesoderm forms somites is known as somitogenesis. This process is highly regulated and involves a complex interplay of morphogens, including members of the Wnt, Notch, and fibroblast growth factor (FGF) signaling pathways. Somites give rise to the vertebrae, ribs, muscles, dermis, and meninges.

Clinical Significance

Abnormalities in the formation or differentiation of the paraxial mesoderm can lead to a variety of congenital disorders, including vertebral defects, scoliosis, and muscular dystrophy. Research into the molecular mechanisms underlying paraxial mesoderm development and differentiation has potential implications for the treatment of these and other mesoderm-related disorders.

See Also

• Mesoderm
• Somite
• Embryogenesis
• Congenital disorder