An experimental investigation into the early development of the chick elbow joint.

The theory that differential growth of opposed chondrogenic centres is important in early joint formation has been tested experimentally by removing structures in relation to the chick elbow joint. The humerus and its cap of differentiating joint cells were found to develop independently of structures distal to them. Removal of the presumptive joint region at early stages resulted in fusion of the humerus with the radius and ulna. Results are discussed in terms of concepts concerning pattern formation of cell types in the early wing-bud.