Analysis of cell movements and fate mapping during early embryogenesis in Drosophila melanogaster

Abstract

The embryonic fate map of the blastoderm stage of Drosophila melanogaster was determined by withdrawing at the blastoderm stage small numbers of cells from different egg lengths (EL) and observing defects at an early segmentation stage with the scanning electron microscope. Using this approach, the presumptive gnathal cells were found between 60 and 70% EL, the presumptive thoracic cells between 45 and 65% EL, and the abdominal segments between 15 and 50% EL. By performing the cell ablations at successively later stages, cell movements could be followed during early gastrulation. The cephalic furrow forms in the anterior portion of the presumptive head region. As the furrow deepens, almost all of the presumptive gnathal cells move into the furrow for a period of time. Analyses of frequency and location of defects suggest that presumptive cells for different segments are contiguous on the blastoderm. The data provide an experimental verification of the morphological fate map of Poulson (1950) and a means of localizing gynandromorph maps to the blastoderm.