Fertilized mouse egg was kept at 37 degrees Celsius in a MatTek coverslip bottom dish on an inverted microscope stage. Imaged using a Leica SP2 AOBS confocal with a 488 nm laser and 10X or 20X objective lens. The pinhole was set to Leica's calculated size for 1 Airy unit, each Z section was scanned in one pass, and the bit depth was 8. Additional information may be found in the Leica generated meta text file attached to the image. Microscopy was performed at the Analytical Imaging Facility of the Albert Einstein College of Medicine.