Female sperm

It has been possible in rare circumstances for a woman to give birth without being impregnated by a man. Parthenogenesis or asexual reproduction is more common among plants, insects, and animals like lizards. For human females to have a "virgin birth" requires them to be chimeras, developed from 2 different zygotes that merged in the womb. If the zygotes are different genders, resulting in an ovary on one side of her body and a testis on the other, a woman can fertilize herself. But now there is a new possibility on the horizon. Stem cell biologist Karim Nayernia of Newcastle University in the U.K. has created primitive sperm cells from female human embryonic stem cells. Irina Kerkis of the Butantan Institute in Saõ Paulo, Brazil, has reportedly made eggs from male mouse embryonic stem cells. This raises possibilities that gay and lesbian couples could have their own biological children. The bone marrow of one woman could be used to fertilize an egg from her partner and a man's skin cells could be used to make eggs, which could be fertilized by his partner’s sperm and implanted into the uterus of a surrogate mother. Although geneticists are skeptical that the reproductive cells will be able to divide properly, and the genetic makeup would mean that the offspring would be the same gender as the parents, the experiments hold the promise of future same-sex human reproduction.

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