Scientists have just created viable embryos without using egg cells. Researchers from the University of Bath were able to trigger normal development in mouse parthenogenotes by injecting sperm. The new findings may eventually help researchers develop better fertility treatments. The details are in a paper that was just published in the journal Nature Communications.
In past studies, researchers were able to induce egg cells into beginning embryonic development without the presence of sperm. These haploid embryos, containing only half of the required genetic material, were non-viable. The embryos, called parthenogenotes, would fail to develop since so many developmental processes require signals and input from sperm cells.
The team was able to produce healthy mouse embryos by injecting sperm into parthenogenotes, provided the injection happened at certain parts of the cell cycle. The embryos developed into adult mice without any health problems. This shows that the beginning of embryonic development doesn’t necessarily require sperm cells. The developing embryos can be injected with sperm later in the cycle, after development has already started.
Previously, it was believed that only an egg cell could reprogram sperm into starting embryonic development. Now, researchers have evidence that a haploid embryo can react similarly with sperm cells. According to this new study, embryos are capable of reprogramming sperm cells. This triggers the same developmental processes that would have occurred with the fusion of an egg and sperm.
While the baby mice were healthy and appeared normal, the researchers did find that their DNA showed different epigenetic markers. This is interesting because it’s the first evidence of unique epigenetic processes leading to normal development. The authors were able to show that different epigenetic pathways can lead to the same type of development.
The team believes that their research may eventually lead to techniques for breeding animals with sperm and non-egg cells, such as skin cells. The findings could also lead to improved treatments for human infertility.
Suzuki, T. et al. Mice produced by mitotic reprogramming of sperm injected into haploid parthenogenotes. Nature Communications (2016).