A contribution to the technique of mouse bone marrow cell culture in semisolid agar.

A method of cultivation of mouse bone marrow cells in semisolid agar is described. Colony-stimulating factor was provided either by a "feeder layer" containing kidney cells (from 8-day-old mice) or by the addition of "lung conditioned medium" or post-endotoxin serum. The effect of various factors and media on the formation of colonies was tested. The best growth of colonies was observed in medium RPMI 1640 or in Eagle's minimal essential medium containing 0.2% bactotryptose supplemented with 20% foetal calf serum. Both the morphology of cells found in the colonies and the proliferative state of the cells that give rise to colonies indicate that CFU-C represent the committed progenitor for myelopoiesis.