Embryos were incubated on yeasted apple juice plates at 25C for 2.25h before being dechorionated in 2.6% sodium hypochlorite, rinsed with water and suspended in PBS 0.5% Truton X-100. They were then resuspended in ice-cold dissociation buffer and dissociated with a clean metal pestle. Cells and tissue fragments were pelleted and then gently resuspended in trypsin-EDTA, pelleted again, and resuspended in dissociation buffer.