[Action of thymic extracts on the growth of different cell populations in vitro]

Thymic, splenic and renal cellular extracts were obtained by tissular grinding and ultra centrifugation, from animals having undergone diverse hormonal treatments. These extracts were added to different cellular populations in culture (carcinomatous HeLa strain, established MRCs strain, primo-culture of human foetal lung strain). The thymic extracts of non treated animals and the splenic extracts rich in FK substance from intact guinea pigs treated by oestrogenes or FSH, provoque an inhibition of tumoral cell growth. The most important effects are obtained with thymus extracts rich in FK substance. The FK substance seems capable of concentrating certain antitumoral thymic fractions.