[Separation of a rat thymocyte population in a ficoll-paque gradient. II. Dynamics of the cell count in different media and the effect of thymolytic factors].

Rat thymocytes were fractioned in the Ficoll-Paque gradient. Cells of various fractions were tested for their ability to survive in several nutritional media at 37 degrees C for 5 hours. In serum-less medium 199, the majority of cells died. The addition of bovine serum (10%) to medium 199 resulted in a sharp increase in the number of live cells in the light fractions. Again, the number of live cells in the light fractions was increased upon the 3 hrs-incubation in the serum-less medium containing hydrocortisone, as well as of cells obtained from animals previously injected with hydrocortisone. The X-irradiation of thymocyte suspension led to an obvious augmentation of the number of live cells, belonging to the medium fraction, after a 5 hours' incubation. A possibility is discussed of the increase in cell numbers of different fractions as the result of the "apoptotic" manner of their death.