(A) Superovulation of donor female mice and production of fertilized oocytes. Fertilized oocytes contain two pronuclei (P), the bigger one derived from the male spermatozoa. PB is the second polar body, and ZP - zona pellucida.

(B) Injection of DNA-construct into pronuclei of fertilized oocyte. HP is designated for the holding pipette and IP - injection pipette accordingly. The injected pronucleus is marked by arrow.

(C) Transfer of embryos into the oviduct of foster mice and carrying them to term.