DIFFERENTIATION IN VITRO OF EMBRYONIC CARTILAGE AND BONE IN A CHEMICALLY-DEFINED MEDIUM.

Summary and conclusions 1. Fell first reported osteogenesis in chick embryo limb buds cultured in vitro in a plasma clot in 1928. Since that time several attempts to repeat her work using a completely-defined chemical medium have failed. Except in one instance, success was achieved only when biologic supplements, e.g., embryo extract or bovine serum albumin, were added to the medium. 2. This communication reports differentiation of embryonic cartilage and bone of the mouse in vitro using a new, completely-defined chemical medium (MAB87/3) which is the simplest thus far reported. Biologic supplements were not necessary. 3. The 14-day embryo limb rudiment develops a rim of perichondrial bone after 5 days of culture in this medium. A further increase in amount of new bone was visible after 12 days of culture.