The mesoderm germ layer further develops into different regions:

• A Paraxial Mesoderm (or Segmental Plate) gives rise to somites. The sclerotome of the somite forms the vertebral body, the myatome produces muscle, and the dermatome contributes to the dermis.

• B Intermediate Mesoderm is the precursor to the urogenital system.

• C Lateral Plate Mesoderm divides into two layers. Somatic mesoderm forms the body walls and limb buds. Splanchnic mesoderm forms mysentry, wall of the digestive tract, and the heart.

• Circulatory System consists of mesodermally derived heart and blood vessels. Development of the vascular system first begins in the blood islands of the yolk sac mesodermal linings. (1)
  

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