By Martin Hutchinson
BBC News Online health staff in Madrid
Men may in future be able to store their sperm at home in the fridge rather than in liquid nitrogen at the fertility clinic.
Home storage is a possibilty
A new air-drying technique may do away with the need for sperm to be deep frozen, with the attendant risks of sperm samples being mixed up and used in the wrong treatment.
However, it would introduce new risks, as men's only stored sperm could be discarded accidentally from the medicine cabinet or fridge during a clear-out.
It used to be believed that if the sperm sample was dried in air the sperm would become useless simply because it could no longer swim when rehydrated.
However, the advent of ICSI - in which a single sperm is injected into the egg directly, means that mobility is no longer an obstacle to fertilisation. Success rates for ICSI are now approaching those of IVF alone in some clinics.
Researchers from the Centre of Assisted Reproduction in Jeddah, Saudi Arabia, developed a new air-drying technique which involved smearing a pellet of washed sperm on to a glass slide and leaving it to dry for a couple of hours inside a cabinet with a controlled flow of air.
This stops the sample being contaminated by dust or bacteria.
When it is needed again, it can be "re-suspended" using a biological fluid designed to keep eggs healthy.
The Jeddah study involved embryos formed from 24 eggs using ICSI - and the re-suspended sperm.
Researchers found that the drying process did not prevent the sperm from taking part in the first stages of fertilisation.
However, the air-dried sperm embryos were slower at getting to the critical eight-cell stage than normal embryos made using fresh sperm.
Overall, the experiment was hailed as a success, and Dr Daniel Imodemhe, who led the project, said: "We believe our study confirms that sperm DNA is resistant to damage by air drying.
"We are greatly encouraged that even under these experimental conditions out of 24 oocytes in the air-dried group, two embryos developed to the blastocyst stage. It's thought only the best quality embryos can continue developing outside the body to this stage."
The move to air-dried, and home-stored, sperm would free IVF clinics from a great deal of expense - current liquid nitrogen facilities cost a great deal to build and run. It is possible these savings could mean cheaper IVF for private patients.