Mesoderm

During early morphogenesis of a eukaryotic vertebrate embryo, the process of Gastrulation produces three distinct germ layers. The layers are called the Ectoderm, Mesoderm and Endoderm. The Mesoderm is the section of cells that lie between the outer ectoderm and inner endoderm^[1] (also see video from Garland Science: ^[2].

During gastrulation, the mesoderm and the endoderm cells become the inner cells of the cell mass by migrating through the primitive streak of the epiblast. The inward migration is called invagination. The primitive node controls and maintains the primitive streak. ^[3]

Depending on the location along the primitive streak, in which the cells enter, determines the type of mesoderm cells they become: ^[4]

• Chordamesoderm cells originated from the anterior region of the primitive node.
• Paraxial mesoderm cells originated from the anterior region of the primitive streak. 
• Intermediate mesoderm cells originate from the midstreak region. 
• Lateral plate mesoderm cells originate from the posterior region of the primitive streak.
  

The four different types of mesoderm cells will develop into different tissues of the body: ^[5]

• Chordamesoderm cells form the neural tube and helps to establish the body axis.
• Paraxial mesoderm cells separate into blocks which form many of the connective tissues in the back, including muscle, bone and cartilage.
• Intermediate mesoderm cells will develop into the genitourinary system.
• Lateral plate mesoderm cells will develop into the organs and blood vessels of the circulatory system. Some lateral plate mesoderm cells will also help to form the lining of the body cells (excluding muscle cells). Some lateral plate mesoderm cells will also further differentiate into extraembryonic membranes which will develop into the umblical cord. ^[6]
  

References

1. ↑ Alberts B. (2008) Molecular Biology Of the Cell, 5th Edition, New York: Garland Science
2. ↑ Garland Science (2014) Supported textbooks, Molecular Biology of the Cell, Fifth Edition. Available at: http://www.garlandscience.com/garlandscience_resources/resource_detail.jsf?landing=student&resource_id=9780815341055_CH22_QTM03 (last accessed 22/11/2014)
3. ↑ Carlson B. M. (2009) Human Embryology and Developmental Biology, 4th Edition, Philadelphia, PA : Mosby/Elsevier
4. ↑ Hall B. K. (2009) The Neural Crest and Neural Crest Cells in Vertebrate Development and Evolution, 2nd Edition, London: Springer
5. ↑ Gilbert S. F. (2000) Developmental Biology, 6th Edition, Sunderland (MA): Sinauer Associates
6. ↑ Hall B. K. (2009) The Neural Crest and Neural Crest Cells in Vertebrate Development and Evolution, 2nd Edition, London: Springer