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==Introduction==

==Introduction==

[[Muscles - Anatomy & Physiology|Muscle]] cells can come from two lineages in the [[Somite Development - Anatomy & Physiology|somite]]. Limb and body muscle develop from hypaxial muscle in the lateral regions of the somite. Back muscle develops from epaxial muscle in the dorsal regions of the somite. Muscle fibres have hundreds of nuclei and function as a syncytium.

[[Muscles - Anatomy & Physiology|Muscle]] cells can come from two lineages in the [[Somite Development - Anatomy & Physiology|somite]]. '''Limb and body muscle''' develop from '''hypaxial muscle''' in the lateral regions of the somite. '''Back muscle''' develops from '''epaxial muscle''' in the dorsal regions of the somite. Muscle fibres have hundreds of nuclei and function as a syncytium.

 

==Muscle Cell Differentiation==

==Muscle Cell Differentiation==

#'''Prescursor''' cells migrate from the dermomyotome.

'''Prescursor''' mesenchymal cells migrate from the dermomyotome. They divide rapidly en route and are undifferentiated. The cells differentiate to form '''myoblasts''', they are still mesenchymal cells, but can no longer migrate as they are differentiated. They have [[Muscles - Anatomy & Physiology|muscle]] gene expression. The '''myotube''' is formed; cells become multi - nucleated to form a syncytium. Muscle enzymes and the '''myofibre''' is produced. Contractile proteins are present.

#*They are mesenchymal

#*Divide rapidly en route and are undifferentiated.

#Cells differentiate to form '''myoblasts'''.

#*Cells still mesenchymal but can no longer migrate as differentiated.

#*[[Muscles - Anatomy & Physiology|Muscle]] gene expression.

#The '''myotube''' is formed; cells become multi - nucleated to form a syncytium.

#*Muscle enzymes are produced.

#The '''myofibre''' is produced.

#*Contractile proteins are present.

 

==Limb Muscle Development==

==Limb Muscle Development==

*[[Muscles - Anatomy & Physiology#Skeletal Muscle|Skeletal muscle]] of the limbs originates from those [[Somite Development - Anatomy & Physiology|somites]] closest to the limbs.

[[Muscles - Anatomy & Physiology#Skeletal Muscle|Skeletal muscle]] of the limbs originates from those [[Somite Development - Anatomy & Physiology|somites]] closest to the limbs. Signalling factors from the limbs cause cells to migrate from the somite and causes the hypaxial lamina to break down, allowing cells to migrate. Few cells migrate; but they rapidly prolifate during migration to increase cell numbers. Muscle precursors migrate into the [[Limb Development - Anatomy & Physiology|limb bud]] (proliferating). At the proximal region of the limb, two populations of cells exists, these are the dorsal and ventral masses. Cells continue migration within these populations. Once cells have reached their destinations, they differentiate.

#Signalling factors from the limbs cause cells to migrate from the somite.

#*Singalling factors cause the hypaxial lamina to break down.

#*This allows cells to migrate.

#*''Few cells migrate; but they rapidly prolifate during migration to increase cell numbers.''

#Muscle precursors migrate into the [[Limb Development - Anatomy & Physiology|limb bud]] (proliferating).

#*At the proximal region of the limb, two populations of cells exists.

#*These are the dorsal and ventral masses.

#Cells continue migration within these populations.

#Once cells have reached their destinations, they differentiate.

[[Category:Developmental Biology]][[Category:Musculoskeletal System - Anatomy & Physiology]]

[[Category:Developmental Biology]][[Category:Musculoskeletal System - Anatomy & Physiology]]

[[Category:To Do - A&P]]

[[Category:To Do - AimeeHicks]]