CALLS for more proof have greeted claims that human sperm have been created in the lab for the first time. If further tests show that the lab-grown sperm are indeed identical to the natural kind, they might be helpful in understanding male infertility.
of the University of Newcastle, UK, and his colleagues treated male embryonic stem cells (ESCs) with a range of substances, which converted them first into germline stem cells and then into spermatogonial stem cells.
These divided to produce 鈥渉aploid鈥� spermatocytes with just 23 chromosomes, which went on to mature into sperm.
Advertisement
Independent researchers are demanding more evidence. 鈥淎lthough they find that some of the sperm cells have tails and can swim, this is not evidence of normality,鈥� says Robin Lovell-Badge, who studies sperm formation at the UK National Institute for Medical Research in London.
91色情片y sperm?
Indeed, all seven mouse pups produced by Nayernia鈥檚 team in 2006 after fusing normal eggs with mouse sperm created in the lab died within five months.
This was because chemical caps called methyl groups had blocked vital genes in the sperm. Nayernia is now carrying out tests to see if the same thing happened with the human sperm.
Nayernia has solved the problem in mice by putting spermatogonial cells into mouse testes before they mature. 鈥淭he sperm then have a normal shape and normal methylation patterns,鈥� he says.
For humans, he claims to have developed 鈥渁rtificial testes鈥� to do the same job.
A more distant possibility is the creation of sperm from a woman鈥檚 cells, allowing a lesbian couple to have a child. Nayernia produced spermatogonial stem cells from female ESCs but they lacked genes needed to mature.
Journal reference: ,
