WEDNESDAY, March 23 (HealthDay News) -- Researchers report that they've grown mouse sperm from testicular tissue in the laboratory, a development that could advance the field of infertility in human males.

Although the findings only apply to mice, "this is a small but important step in understanding how sperm are formed, which may, in time, lead to us being able to grow human sperm in the laboratory," said Dr. Allan Pacey, senior lecturer in andrology at the University of Sheffield in England, who is familiar with the study results.

Sperm production is highly complex, the authors explained in background information in the study. Sperm previously created in a laboratory from mammal tissue didn't fulfill its purpose, Pacey said, noting offspring produced from it soon died.

For this study, published in the March 24 issue of the journal Nature, researchers took tissue from the testes of baby mice and coaxed it into producing sperm cells. They then inseminated female mice, which had healthy babies.

Moreover, the frozen sperm remained viable for months, the authors said.

Physicians caution that the research would need confirmation by other studies in animals and humans before it could become feasible to grow human sperm in a laboratory. But the potential exists for the procedure to help some cases of male infertility.

"It will be useful for diagnosis and treatment of infertility in future, for sure," said study co-author Dr. Takehiko Ogawa, a urologist at Yokohama City University Graduate School of Medicine in Japan.

And the sperm-growing procedure shouldn't be expensive, Ogawa added.

Boys with childhood cancer are one potential treatment group because chemotherapy treatments can cause infertility. Before undergoing chemo, it's conceivable that young men can have their sperm stored for later use. But if the boys are too young to produce sperm, the laboratory technique may hold some promise.

"Years later, grown sperm in the laboratory could allow them to have children that were genetically theirs," Pacey said. However, legal issues may arise regarding obtaining testicular tissue from kids who aren't old enough to give consent, he added.

Dr. Robert D. Oates, professor of urology at Boston University School of Medicine, said: "We're doing such a great job of curing people that we need to think about the other long-term issues, of which fertility is one. It's nice that they can have a full adulthood like the rest of us do and are able to have kids."

As for infertile men, eventually it may be possible to take their tissue and grow sperm outside their bodies instead of searching for rare working sperm through biopsies of their testicles, said Dr. Ian Cooke, emeritus professor of obstetrics and gynecology at the University of Sheffield.

But if genetic problems caused their infertility in the first place, growing sperm outside the body wouldn't make any difference, Cooke said.

More information

For more about infertility, visit the U.S. National Library of Medicine.