Abstract A technique is described whereby avian egg contents removed from the shell after 72 hours of normal incubation may be successfully cultured for extended periods of time (81% for 15.5 days), many of the embryos reaching Hamilton-Hamburger Stage 40–41 (14–15 days). Egg contents are suspended in commercial plastic wrap held in place in culture vessels consisting of modified Playtex nurser holders. Culture vessels are lowered into Kerr wide mouth quart mason jar saturation humidity chambers which have been attached to aquarium lines inside of a modified Forma model 329 CO2 incubator. Use of a 5–8% CO2 atmosphere substantially improved embryonic survivability.