Schematic diagram of the methods for busulfan emulsification and injection into eggs. (A) Internal pressure-type micro kit (IMK-20; MCtech, Siheung, Korea). (B) Busulfan solubilized in 10% N,N-dimethylformamide in phosphate-buffered saline. (C) Hydrophobic membrane with 10-μm pore diameter. (D) Sesame oil with polyglycerol polyricinoleate. (E) Sharp needle. (F) Blastoderm. (G) Egg yolk. (H) Egg white. (I) Air space.