Role of cell sorting in pattern formation in Dictyostelium discoideum.

To examine the relationship between cell sorting and cell differentiation in the development of Dictyostelium discoideum, labeled cells grown in the absence of glucose [G(-)cells] and unlabeled cells grown in its presence [G(+)cells] were mixed and either allowed to undergo normal morphogenesis or cultured under submerged conditions. Changes in the distributions within a cell aggregate of labeled cells and cells stained with the conjugated antispore serum (prespore cells) were followed on the same sections by the methods of autoradiography and immunohistochemistry. In normal morphogenesis, differentiation of prespore cells apparently initiated and proceeded coincident with sorting out between G(+) and G(-) cells, during formation of standing slug. By contrast, within an aggregate formed under submerged conditions, prespore cells began to differentiate long before G(+) and G(-) cells were sorted out, indicating that the cell sorting is not a prerequisite for the cell differentiation. The sorting out, however, brought about an accumulation of prespore cells in a hemisphere, thus producing a prestalk-prespore pattern within the aggregate.