Comparison of growth characteristics of experimental tumours and derived cell cultures

Cells from seven different rat tumours and a mouse sarcoma have been transplanted in syngeneic animals and were cultured in vitro. Tumours produced by inoculation of cultured cells in animals have been compared with the primary tumours. For the transplanted tumours, volume doubling times, T d, have been compared with doubling times, T d(cult), of cell numbers in cultures. Volume doubling times of the transplanted tumours generally decrease with increasing volume. At volumes of about 0-5 cm3, T d values range from 2-2 days to 10 days, while T d(cult) values ranged from 11 to 24 hr. A systematic correlation between T d and T d(cult) could not be established. During sequential transplantation of the tumours for many generations, as well as during continuous propagation of derived cell cultures, significant changes occurred which resulted in a decrease in the expression of differentiation characteristics in tumours.