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Scientists have discovered a way to produce eggs from scratch, in mini ovaries grown in tubes, opening up new avenues for the field of reproductive medicine and fertility.
The researchers, led by Katsuhiko Hayashi of Kyushu University, Japan, created of a mouse ovary-like tissue, called an “ovarioid.” They developed the ovarioid with a cocktail of chemicals that induce stem cells to form ovarian-like tissue. This helped them overcome previous limitations, where forming eggs in a lab required fresh ovarian tissue, usually taken from female mice. These results are the very first time that all components, ovary-like tissue and eggs, were made entirely from stem cells.
Hayashi has made other great strides in reproductive biology. In 2011, he and colleagues generated sperm from stem cells, also in mice. Hayashi's group also developed an original method for growing eggs from stem cells with fresh ovary tissue in 2016. The new findings, published in the journal Science in July, could eventually allow people who have damaged or lost ovarian tissue and same-sex couples to potentially have biological children, using their stem cells as the base for generating eggs.
Despite these strides in mice, there currently remains a bottleneck for developing these technologies in humans, as the methods would need to be adapted for developing human eggs. Collecting fresh ovarian tissue from humans also has huge ethical and technical implications, and this idea could circumvent that particular hurdle. But developing human eggs or ovaries from stem cells should be discussed by scientists, policy makers, and ethicists.