Genetically manipulated embryos were dissected in ice-cold 1×PBS, followed by imaging in a drop of DMEM medium supplemented with 10% foetal bovine serum (FBS) under a Nikon Eclipse Ti2 inverted microscope. Embryos were then rinsed in ice-cold 1×PBS, transferred into an Eppendorf tube containing 35 µl 0.25% Trypsin/0.02% EDTA Solution A, and incubated at 37 °