Congenital fusion of bones: radiology, embryology and pathogenesis.

Congenital fusion of bones of the limbs, a recurrent feature in thalidomide embryopathy, is discussed in terms of embryology. It is deduced that congenital fusion is neither a bone disease nor a cartilage disease, but a disorder of organisation of mesenchyme in the fifth week of life. It is suggested that the organising tissue is the sensory nerve. Hereditary influence is briefly mentioned.