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*Somitic derivatives form according to the somite's position along the anterior - posterior axis.
 
*Somitic derivatives form according to the somite's position along the anterior - posterior axis.
 
**Formation of sclerotome, myotome and dermotome is not intrinsic, but governed by '''environmental signals'''.
 
**Formation of sclerotome, myotome and dermotome is not intrinsic, but governed by '''environmental signals'''.
**However, positional information is '''predetermined and intrinsic''' to the somite. Positional information is important to form the appropriate type of vertebrae, [[Muscles - Anatomy & Physiology|muscle]] and [[Skin - Anatomy & Physiology|skin]]long the anterior - posterior axis.
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**However, positional information is '''predetermined and intrinsic''' to the somite. Positional information is important to form the appropriate type of vertebrae, [[Muscles - Anatomy & Physiology|muscle]] and [[Skin - Anatomy & Physiology|skin]] along the anterior - posterior axis.
 
**Positional information is governed by HOX gene expression. Each somite expresses a unique number of HOX genes.
 
**Positional information is governed by HOX gene expression. Each somite expresses a unique number of HOX genes.
 
*The chick has 12 somites.  
 
*The chick has 12 somites.  
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