According to Chinese team of scientists a new discovery has been made which will boost male fertility.
But scientists also claim that in future the women can have babies without men, everything could be done via artificial sperm.
The team from China claims they have created healthy mouse babies by injecting laboratory-made sperm into eggs to produce mouse offspring.
The scientists claim their stem cell technique could pave the way for new treatments for male fertility.
But British experts have called for the results to be independently verified and pointed out that any practical application is likely to be a long way off.
The mouse cells produced were technically “spermatids” – undeveloped sperm that lack tails and cannot swim.
Yet when they were injected into mouse eggs, mimicking a common IVF technique called Icsi (intracytoplasmic sperm injection), they delivered viable embryos and healthy, fertile babies.
In the UK, using spermatids in the same way to produce a pregnancy would be illegal.
Dr Jiahao Sha, from Nanjing Medical University, who co-led the research, published the results in the peer-reviewed journal Cell Stem Cell.
He said: “If proven to be safe and effective in humans, our platform could potentially generate fully functional sperm for artificial insemination or in-vitro fertilization techniques.
“Because currently available treatments do not work for many couples, we hope that our approach could substantially improve success rates for male infertility.”
The scientists began with stem cells taken from mouse embryos which were exposed to a carefully mixed cocktail of chemicals.
This triggered their transformation into primordial germ cells, the first step on the developmental path to becoming sperm.
Next, the germ cells were exposed to testicular cells and testosterone in an attempt to mimic the natural environment of the testes.
In test with mouse eggs, the spermatozoids were capable to produce embryos which developed normally.
Around 15% of couples are affected with infertility, and the third of them can be traced to the men.
A major cause of male infertility is the failure of pre-cursor cells in the testes to undergo a special type of cell division called meiosis.
In one research from 2014 was established and proven with evidences that the DNA content can be corrected in in the cell nucleus at specific meiotic stages, normal chromosome number and organization, and the ability of the engineered cells to produce viable offspring.
The Chinese team claims to have passed all these tests.
Dr Sha said: “Our method fully complies with the gold standards recently proposed by a consensus panel of reproductive biologists, so we think that it holds tremendous promise for treating male infertility.”
The UK scientists respect and praise the Chinese revelation but they still think that there are few obstacles that should be pass before the sperm can be used to infertile men.