Lateral plate mesoderm
Transverse section of a chick embryo of forty-five hours' incubation. *Axial mesoderm: yellow, atnotochord. *Paraxial mesoderm: red, atsomite. *Intermediate mesoderm: purple, nearWolffian duct. *Lateral plate mesoderm: purple, divided into "Somatic mesoderm" and "Splanchnic mesoderm".
Diagram of vertebrate embryo showing divided lateral plate mesoderm forming theintraembryonic coelom. Somatic mesoderm at outer layer, splanchnic at inner layer.
Details
Carnegie stage	9
Precursor	Mesoderm
Gives rise to	Somatopleure,splanchnopleure
Identifiers
Latin	mesoderma laminae lateralis
TE	plate mesoderm_by_E5.0.3.0.0.0.2 E5.0.3.0.0.0.2
Anatomical terminology [edit on Wikidata]

Thelateral plate mesoderm is themesoderm that is found at the periphery of theembryo. It is to the side of theparaxial mesoderm, and further to theaxial mesoderm. The lateral plate mesoderm is separated from the paraxial mesoderm by a narrow region ofintermediate mesoderm. The mesoderm is the middle layer of the threegerm layers, between the outerectoderm and innerendoderm.

During the third week ofembryonic development the lateral plate mesoderm splits into two layers forming theintraembryonic coelom.

The outer layer of lateral plate mesoderm adheres to the ectoderm to become the somatic or parietal layer known as thesomatopleure. The inner layer adheres to theendoderm to become the splanchnic or visceral layer known as thesplanchnopleure.

The lateral plate mesoderm will split into two layers, thesomatopleuric mesenchyme, and thesplanchnopleuric mesenchyme.

• Thesomatopleuric layer forms the future body wall.
• Thesplanchnopleuric layer forms thecirculatory system.

Spaces within the lateral plate are enclosed and forms theintraembryonic coelom.

It is formed by the secretion ofBMP-4 by the ectoderm.^[1]

Lateral plate mesoderm gives rise to the serosal mesoderms.^[2]

• forms a ventral layer associated withendoderm, thesplanchnopleuric mesoderm. This forms the viscera and heart
• forms a dorsal layer associated withectoderm, thesomatopleuric mesoderm. This forms the body wall lining and dermis.
• Abdominal portion becomes contained indorsal mesentery, part of the serosal mesoderm.
• When the two layers form, a cardiogenic plate is visible. Later, this will form the myocardial primordium, which will contribute to the tubular heart.

In the 4th week the coelom divides intopericardial,pleural andperitoneal cavities.^[2]

• First partition: is theseptum transversum.

• This will be translocated later into the diaphragm andventral mesentery.
• Divides thecoelom into primitive pericardial and peritoneal cavities

• Pleuropericardial folds appear on the lateral wall of primitive pericardial cavity, which will eventually cause a partition to form the pericardial and pleural cavities.
• Communication between these partitions formed by the pericardioperitoneal canals. However,pleuroperitoneal membranes will grow to fuse with the septum transversum to close off these canals.

• At day 22,lung buds form, remaining ensheathed in a splanchnopleuric mesoderm

Cells from the lateral plate mesoderm and the myotome migrate to the limb field and proliferate to create the limb bud. The lateral plate cells produce the cartilaginous and skeletal portions of the limb while the myotome cells produce the muscle components. The lateral plate mesodermal cells secrete a fibroblast growth factor (FGF7 and FGF10, presumably) to induce the overlying ectoderm to form an important organizing structure called theapical ectodermal ridge (AER). The AER reciprocatively secretes FGF8 and FGF4 which maintains the FGF10 signal and induces proliferation in the mesoderm.^[3] The position of FGF10 expression is regulated by Wnt8c in the hindlimb and Wnt2b in the forelimb. The forelimb and the hindlimb are specified by their position along the anterior/posterior axis and possibly by two T-box containing transcription factors: Tbx5 and Tbx4, respectively.

• 
  Model of human embryo 1.3 mm. long. (Splanchic mesoderm labeled at left, somatic mesoderm at top right

• List of human cell types derived from the germ layers

This article incorporates text in thepublic domain frompage 50 of the 20th edition ofGray's Anatomy(1918)

• Swiss embryology (fromUL,UB, andUF)hdisqueembry/triderm08

• Wikipedia articles incorporating text from the 20th edition of Gray's Anatomy (1918)
• Embryology of urogenital system
• Mesoderm