In a scientific first, full term development of healthy babies has just been achieved in mice by injecting mouse sperm into non-egg cells, according to new research that has future implications for breeding endangered species and for human fertility treatments, including those that could allow gay male couples to have their own biological children.
The discovery, reported in the journal Nature Communications, challenges two centuries of dogma -- originating at around 1827, when early embryologists first observed mammal eggs -- claiming that only an egg cell is capable of reprogramming sperm to permit the development of a mammal embryo.
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Ironically, the new research that could empower men builds on a phenomenon known as parthenogenesis, aka "virgin birth," which has been documented in a number of species, such as certain fish, reptiles, insects and amphibians, but not in mammals. When such births occur, an embryo develops from an unfertilized egg cell, allowing females to reproduce without males.
Previously, scientists were able to "trick" mammal eggs into developing into embryos without fertilization, but the resulting embryos -- called parthenogenotes -- died after a few days in the lab because key processes requiring input from sperm did not happen.
For the recent study, scientists overcame this problem by developing a method of injecting mouse parthenogenotes (which consist of mitotic cells, meaning cells that divide to form two identical cells) with sperm (which is a differentiated, or specialized, cell). The outcome resulted in healthy baby mice, with a success rate of about 24 percent.
"This work shows for the first time that a mitotic cell can completely reprogram a differentiated cell, with the outcome being the birth of live young," senior author Anthony Perry, a molecular embryologist at the University of Bath, told Discovery News. "Yes, the cells are special -- a parthenogenote and a sperm -- but imagine if any mitotic cell could reprogram a sperm in the same way. Then there would be no need for eggs."