Primary Populations - Primary cell populations are obtained from intact animal tissues and grown on glass or plastic surfaces for the first time. Specimens are treated with trypsin to separate individual cells. The cell suspensions are centrifuged, counted and tested for viability by dye exclusion. Cells are either preserved frozen or seeded into culture vessels.
Diploid Lines - Diploid cell lines are derived from primary cell populations that (a) have been sub-cultivated several times. (b) retain the normal chromosome constitution of the tissue of origin and (c) are capable of a finite number of sub-cultivations.
Heteroploid Lines - Heteroploid cell lines are cell populations that (a) can be sub-cultivated indefinitely, (b) reveal abnormal chromosome number or morphology and (c) possess other properties that distinguish them from normal cells.