Research is currently investigating the possibility of same-sex procreation, which would produce offspring with equal genetic contributions from either two females or two males.[7] This form of reproduction has become a possibility through the creation of either female sperm (containing the genetic material of a female) or male eggs (containing the genetic material of a male). Same-sex procreation would remove the need for lesbian and gay couples to rely on a third party donation of a sperm or an egg for reproduction.[8] The first significant development occurred in 1991, in a patent application filed by U.Penn. scientists to fix male sperm by extracting some sperm, correcting a genetic defect in vitro, and injecting the sperm back into the male's testicles.[9] While the vast majority of the patent application dealt with male sperm, one line suggested that the procedure would work with XX cells, i.e., cells from an adult woman to make female sperm.