GROWTH OF CELLS IN AGITATED FLUID MEDIUM

One of the difficulties arising from the use of tissue cultures in physiological studies has been the accurate evaluation of growth under experimental conditions. The methods which have been developed, in most cases, have been confined to a particular type of measurement which gives an indirect measure of the actual number of cells present a t any one time. When compact cell colonies are formed, the determination of cell number may be difficult or impossible, and the evaluation of the conditions of the environment to which each individual cell of the colony is exposed often cannot be determined. The cells on the edge of the colony are exposed directly to the nutrient fluid, while those in the center are exposed partially or exclusively to living or handicapped cells. In the method to be reported here, cells which do not form colonies and are maintained in suspension have been used. The cell suspension is kept agitating so that the medium is mixed continually and all of the cells are exposed to uniform environmental conditions. Samples of the suspension are removed for cell counts. Since Harrison’O 9 l1 developed the first method for growing animal tissues in vitro, it was thought by many investigators that a supporting framework consisting of a substance such as fibrin was necessary for optimum growth of tissues in * Since then, it has been found that, in the case of many cell types, good growth occurs on a glass surface in a liquid l2 It has been found now that cells can be grown without being permanently attached to a surface. This method was first reported a t the meetings of the American Association for Cancer Research held in April 1953.