Tumorigenecity: Isoenzyme: Histopathology: choriocarcinomaSubculture: Remove medium, add fresh 0.25 % Trypsin 0.02 % EDTA solution, stand culture flask at 37Split ratio: Media change: Remove two thirds of medium and add fresh medium (depending on cell density) every 2 to 3 daysReverse transcritase: Production.