Scientists admit that such a scenario is “speculative and fanciful”, but do not rule it out in principle.
Working with mice, the team produced healthy offspring while bypassing the normal process of fertilising an egg cell with sperm, and without cloning.
The extraordinary result means that sperm could potentially be fused with ordinary cells derived from skin or other tissue to create viable embryos.
It also raises the possibility of ethically questionable applications that turn nature on its head by doing away with the female side of reproduction. Gay men, for instance, could have babies with each other, and a man could even fertilise his own cells to produce offspring containing a mixture of genes inherited from him and his parents.
More realistically, the technique could allow women whose fertility has been wiped out by cancer drugs or radiotherapy to have their own children.
Conception using sperm and somatic cells would also aid the preservation of endangered species, as it avoids the need to recover eggs.
Lead scientist Tony Perry, a University of Bath molecular embryologist, said: “Our work challenges the dogma, held since early embryologists first observed mammalian eggs around 1827 and observed fertilisation 50 years later, that only an egg cell fertilised with a sperm cell can result in live mammalian birth.”
However, he stressed that the early work demonstrates only a principle, and major hurdles would have to be overcome before reproduction without egg cells became technically feasible.
“This is speculative — it’s entirely speculative and fanciful,” said Dr Perry.
For the experiment, the scientists started off by creating ‘parthenogenote’ mouse embryos. These are all-female embryos made without sperm by tricking an egg into developing as if it has been fertilised.
Mammalian embryos produced this way usually die after a few days because they lack the right programming. However, Dr Perry’s team of researchers found that injecting the parthenogenotes with sperm transformed them into normal embryos that went on to produce healthy offspring.
The outcome, reported in the journal Nature Communications, is hugely significant because parthenogenotes share much in common with ordinary cells such as skin cells. Both kinds of cell multiply by means of a non-sexual form of cell division known as mitosis.
In the study, 30 mouse pups were born with a success rate of 24%. This compares with a 1% to 2% success rate for offspring created by the Dolly the Sheep method of cloning by transferring DNA to donated eggs. Some of the mice went on to have offspring themselves, and a number had offspring that went on to have their own pups. Fertility is generally seen as a sign of fitness and good health.
Dr Perry said his team is planning to take the next step of attempting to produce live offspring from ordinary non-egg cells rather than parthenogenotes..
Embryologist Robin Lovell-Badge, from The Francis Crick Institute in London, said: “I’m not surprised that the authors are excited about this. I think it is a very interesting paper, and a technical tour de force. And I am sure it will tell us something important about reprogramming at these early steps of development.”