At the end of the incubation, place the eggs onto the laboratory benchtop. Use a syringe to perforate the film dressing of each egg and apply about 300 microliters of 4% paraformaldehyde over each chorioallantoic membrane to slightly stiffen the tissue to facilitate the harvesting process.
Using scissors, remove the upper half of the eggshell with the chorioallantoic membrane attached. Reduce the size of the shell to approximately 3 centimeters in diameter, keeping the portion of the chorioallantoic membrane where dorsal root ganglion and tumor cells were grafted within the center of the shell fragment. Then, grasp the chorioallantoic membrane with fine forceps and detach the tissue from the eggshell for transfer into one well of a 6-well plate containing 2 milliliters of 4% paraformaldehyde per well.