CELL CYCLING AND PATTERNED CELL-PROLIFERATION IN THE WING PRIMORDIUM OF DROSOPHILA

The pattern of cell proliferation in the Drosophila imaginal wing prim ordium is spatially and temporally heterogeneous. Direct visualization of cells in S, G(2), and mitosis phases of the cell cycle reveals sev eral features invariant throughout development, The fraction of cells in the disc in the different cell cycle stages is constant, the majori ty remaining in G(1). Cells in the different phases of the cell cycle mainly appear in small synchronic clusters that are non-clonally deriv ed but result from changing local cell-cell interactions. Cluster sync hronization occurs before S and in the G(2)/M phases. Rates of cell di vision are neither constant nor clonal features. Cell cycle progressio n is linear rather than concentric. Clusters appear throughout the dis c but with symmetries related to presumptive wing patterns, compartmen t boundaries, and vein clonal restrictions.