Mesoderm

The mesoderm is one of the three embryonic sheets or cell layers that make up the embryo. It can be performed by enterocelia or schizocelia from a blastocyst in the process called gastrulation. In the process prior to the formation of the mesoderm and gastrulation, there are two layers, the hypoblast and the epiblast. The epithelial cells of the epiblast transform into mesenchymal cells with the ability to migrate, invaginate, and give rise to the 3 embryonic layers, pushing the epithelium of the hypoblast into the yolk sac.

Through the process of mitosis of the ectoderm a third layer of cells originates, located between the ectoderm and the endoderm called the mesoderm. The animals that have this third embryonic leaf are called triblastic and belong to the Bilateria group. It is commonly divided into paraxial mesoderm, intermediate mesoderm, and lateral mesoderm.

In vertebrates, throughout development the mesoderm will differentiate into five types that will form the different mesenchymal tissues:

• Mesodermo cordado (cordamesoderm). This tissue will result in notocorda, a transient organ whose most important function is the induction of the formation of the neural tube and the establishment of the antero-posterior axis.

• Mesodermo dorsal somtico. The cells of this tissue will form the somites, blocks of mesodymal cells located on both sides of the neural tube that will develop to give rise to other tissues such as cartilage, muscle, skeleton and dorsal dermis.

• Intermediate Mesoderm. He'll form the excretor.

• Mesodermo latero-ventral. It will give rise to the circulatory apparatus and it will tap all the body cavities and all the extraembrionary membranes important for the transport of nutrients.

• Precordal Mesoderm. It will give rise to the mesenchymal tissue of the head, which will form many of the connective tissues and the musculature of the face.

Mesoderm in humans

The mesoderm appears during the trilaminar period, which develops in the third week of gestation. Towards the end of it, when the gastrulation process begins to end, the intraembryonic mesoderm on each side of the midline differentiates into paraxial, intermediate, and lateral mesoderm.