The skeletal system (consisting of cartilages and bones) and articular system (comprising joints of the body) develop from mesoderm. The mesoderm gives rise to a pluripotent embryonic connective tissue, called mesenchyme, which is capable of differentiating into a diverse variety of derivatives. In the region of pharyngeal arches a special variety of mesenchyme, called ecto-mesenchyme, is also found. The ecto-mesenchyme is derived from neural crest cells (which are themselves ecto-dermal derivatives).
The mesenchyme is a loosely arranged tissue composed of roughly stellate (star-shaped) cells having many processes. The irregular spaces between the cells are filled with a structureless, semifluid, jelly-like intercellular substance.
When the mesenchyme differentiates into any specific type of tissue, changes occur in the shape and structure of cells and in the composition of the ground substance. Histogenesis of cartilage and bone tissue from the mesenchyme will now be described.