Cell cycle parameters of 3T3 cells cultured as aggregates.

BALB/c 3T3 cells cultured as aggregates were examined by two independent techniques to determine whether or not cells accumulated at a specific point in the cell cycle, and if so to determine the point at which they accumulate. Replating cells onto dishes followed by pulse labeling with [3H]thymidine and autoradiography indicated that aggregate-cultured cells were in the same phase of the cell cycle as cells cultured as confluent monolayers. Flow microfluorometry confirmed that 75% of the aggregate-maintained cells were arrested in G0 or G1, with 25% distributed throughout the rest of the cell cycle. Labeling and mitotic indices of cells in aggregates were also consistent with about 20 to 25% of the cells being in S+G2=M phases of the cell cycle at any time.