The Upright Ape: A New Origin of the Species

by Aaron G. Filler, MD, PhD

Figure 7-4 The Role of the Somites in Vertebrate Embryonic Development

Embryology of the Somites

Figure 7-4 Somites,  somitomeres and neural crest cells have tissue identities determined as serially repeating structures by Hox genes.

(A) Body segments in vertebrate animals form as clumps of tissue called somites.

(B) Somites develop into various types of tissue including the bony vertebrae

(C) the muscles of that body segment.

(D) Neural crest cells in serially repeating groups migrate within a segment to reach their destined positions to form nerve ganglia and other tissues.

(E,F) The head forms from segmented tissues – some have been called somitomeres.

Figure credits -

A, B, C - From: Kardong 2005, p.297 - Vertebrates: Comparative Anatomy, Function, Evolution 4th ed, by Kenneth Kardong. © The McGraw-Hill Companies, Inc., drawings reproduced by their permission.

D, E, F - Redrawn, modified after: Liem (2001) Functional Anatomy of the Vertebrates, An Evolutionary Perspective, 3rd Edition by Liem. 2001.

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