The japanese scientists present their results in the journal "science". The researchers had already succeeded in similar experiments with sperm before.
Katsuhiko hayashi of kyoto university and his team used two types of stem cells for their experiments: firstly, embryonic stem cells, which are derived from embryos and can be differentiated into any cell of the body. On the other hand, so-called induced pluripotent stem cells (ips cells), which – ethically more harmless – are obtained from already matured body cells and can still differentiate into numerous different types of cells. These two types of stem cells were first transformed by the researchers through genetic manipulation into cells that closely resemble germ cells. From the primordial germ cells egg and sperm cells emerge.
The researchers then cultured these cells together with cells from the ovaries of mice to create a kind of artificial ovary. They showed that their germ cells developed in a similar way to those in a natural embryonic ovary. Finally, they transplanted the complex into the ovaries of mice. There, the cells developed into eggs, which the researchers then removed, allowed to mature in the laboratory and finally fertilized artificially. The resulting embryos were transplanted back into female mice.
In both cases they received mouse offspring, which continued to multiply. The success rate is not yet very high, but in principle the work provides a solid basis for further developing the development of oocytes in humans in the laboratory, the researchers say. This is a central prerequisite for being able to treat certain forms of infertility in humans.
Last year, another team of japanese researchers also presented a method for growing functional sperm cells in the laboratory. The scientists had taken testicular tissue from mice and stimulated the early developmental stages of sperm contained therein to mature. They then used the sperm to fertilize oocytes, which eventually gave rise to several mouse babies.