Collagen synthesis in vitro by embryonic spinal cord epithelium

Isolated spinal cords from chick embryos (stages 12 to 15) were incubated in vitro with radioactive proline. The proteins synthesized were fractionated by coprecipitation with added carrier collagen, followed by molecularsieve and ion-exchange chromatography. A portion of the isotopically labeled proteins were found to be collagen molecules consisting only of alpha1 chains.