Biochemical criteria for the in vitro differentiation of embryoid bodies produced by a transplantable teratoma of mice. The production of acetylcholine esterase and creatine phosphokinase by teratoma cells

When embryoid bodies are grown in suspension culture in vitro, they undergo only a limited amount of morphological development. When these same embryoid bodies are permitted to attach to the surface of a culture dish, a wide variety of new morphological cell types appear. Suspension cultures of embryoid bodies do not contain significant detectable levels of acetylcholine esterase or creatine phosphokinase. These same enzymes however are produced in cell cultures derived from embryoid bodies attached to the culture dish surface. Polyacrylamide gel electrophoresis has been employed to demonstrate that the electrophoretic form of creatine phosphokinase produced by teratoma cells in culture is the brain form of the enzyme. Solid transplantable tumors containing only embryonal carcinoma cells (stem cells) do not contain either of these enzymatic activities. Well differentiated transplantable teratomas contain both enzymes.