Sorting out of limb bud cells in monolayer culture

To examine differences in the surface properties of limb bud cells, we mixed cells from the progress zone at different stages or from different positions along proximodistal axis of chick and quail wing limb buds. To identify the origin of cells, a chick-specific antibody was used in a mixed culture of chick and quail cells, or cells from one of the stages were labeled with a fluorescent dye, PKH-26. Within 18 hours in mixed culture, cells segregated from each other and formed patches of various sizes. The process zone cells at early developmental stages mixed homogeneously with the cells from proximal region of old limb buds and the progress zone cells at late stages mixed homogeneously with the cells from distal region of the old limb buds. These results suggest that surface properties of cells in progress zone change during limb bud development and vary along the proximodistal and anteroposterior axes of the limb bud and that these differences in surface property may correspond to the positional values for limb pattern formation.