File:Mesoderm cartoon 06.jpg

2. Somite Development - Early Somite

• Paraxial mesoderm towards the rostral (cranial) end, begins to segment forming the first somite.
• Somites are then sequentially added caudally in pairs.
• The somite surface cells undergo a mesenchymal to epithelial transition, forming a transient epithelial covering on each somite.
• The mesoderm under the surface remains as mesenchyme and proliferates.
• The early forming somites have a cavity (somitocoel) in their core that is lost as the somite matures.

Note - the cartoons show just the embryo righthand side mesoderm development (the same events occur on the lefthand side).

Somite Links: 1 paraxial | 2 early somite | 3 sclerotome and dermomyotome | 4 dermatome and myotome | 5 somite spreading | SEM image - Human Embryo (week 4) showing somites | Movie - somitogenesis Hes expression

• Somite Cartoons
• 

  paraxial

• 

  early somite

• 

  sclerotome and dermomyotome

• 

  dermatome and myotome

• 

  somite spreading

Cite this page: Hill, M.A. (2024, April 25) Embryology Mesoderm cartoon 06.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Mesoderm_cartoon_06.jpg

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G