Chondrogenesis in outgrowths of muscle tissue onto modified bone matrix in tissue culture.

Connective tissue outgrowths of muscle occur in vitro onto a substratum of bone matrix gelatin (BMG) chemically modified by various inorganic and organic cations or anions. Outgrowths onto BMG denatured by lyotropic concentrations of Ca2+ or complexed by only 1 mmole/1 of Cu2+ differentiate into fibrous tissue only. Onto BMG complexed with either positively or negatively charged organic molecules, the product was also fibrous tissue. Outgrowths onto undenatured and partially recalcified MBG differentiated into cartilage. These observations substantiate the view that differentiation of cartilage in tissue culture occurs in response to the undenatured form of a bone matrix protein molecular and not an unspecific surface net electrochemical charge.