for National Geographic News
For the first time scientists have been able to produce viable sperm from the tissue of sexually immature mammals—and at the same time produce sperm of one species in the body of another species.
Researchers report that by transplanting tissue from the testicles of newborn pigs and goats onto the backs of laboratory mice the tissue not only survived but it started to produce mature, fully functional sperm of the donor species.
The ability to produce virtually unlimited amounts of sperm using this technique could conceivably be used to help human couples struggling with male fertility problems, preserve species close to extinction, and in animal husbandry.
Mouse-Grown Sperm
Earlier techniques using isolated germ cells worked only in closely related species of rats and mice. To overcome this problem, scientists at the University of Pennsylvania grafted fragments of testicular tissue taken from newborn pigs, goats, and mice onto the backs of nude mice. Testicles are the male reproductive gland, responsible for producing testosterone and sperm cells.
More than 60 percent of the grafts of all three species produced mature, fully functional sperm.
"The biggest challenge was to produce sperm from testis tissue that is sexually immature," said Ina Dobrinski, a veterinarian researcher at the University of Pennsylvania and co-author of the study published in the August 15 issue of the journal Nature.
"In an adult you can always save sperm, but say you have a boy child who is about to undergo chemotherapy. Using this technique you could save a little of the testis tissue to generate sperm when he is grown up. Before this, there was no option for the sexually immature individual."
The technique also has applications in animal husbandry. Livestock producers could use testicular tissue of genetically very valuable animals to generate sperm and perpetuate a breed or simply the bloodlines of animals possessing valued traits like the ability to produce a lot of milk or wool.
Preserving and enhancing populations of endangered species is another potential application for the technique.
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