Separation of resting and proliferating granulocytic precursors.

We have obtained cells in various stages of granulocytic development by a combination of isopycnic separation and electronic cell sorting. Not only were immature cells (blast cells, promyelocytes and myelocytes) separated from mature cells (bands and polys), but the immature cells were separated into proliferating (S + G2 + M) and resting (Go/G1) compartments of the cell cycle. This permits the study of the morphological and biochemical changes associated with development apart from those changes associated with proliferation.