Which germ layer contributes to the skeletal precursor cells in limb development?
Lateral plate mesoderm constitutes the structural core of emerging limb buds and exclusively provides skeletal precursor cells, whereas ectoderm forms the apical ectodermal ridge and somitic mesoderm supplies migrating myoblasts. Within the bud, lateral plate-derived mesenchyme undergoes Sox9-dependent condensation, then differentiates into chondrocytes that generate stylopod humerus-femur, zeugopod radius-ulna-tibia-fibula, and autopod digit templates. This tissue secretes FGF10 to induce FGF8 in overlying ectoderm, establishing reciprocal epithelial-mesenchymal loop. Neural crest contributes to craniofacial but not appendicular skeleton. Conserved across chick mouse human models, this mechanism illustrates classic embryological principles integrated with modern molecular genetics.
Ref: Gilbert, Developmental Biology, 12th ed., Chapter 19: Limb development – lateral plate mesoderm skeletal origins.