In one study Japanese fertility experts report two world 'firsts' mice born from frozen immature testicular tissue taken from one set of mice and matured in others, and a rabbit born after maturing testicular tissue in a host mouse.
In the second study UK researchers have shown that it is feasible to obtain semen from boys as young as 12 and they are calling for sperm banking to be offered to all cancer patients from the age of 12.
The Japanese study
The Japanese researchers are looking for ways to help babies and young boys whose testicles do not contain mature sperm and for whom there is no effective way as yet to preserve fertility after cancer treatment.
They froze and thawed pieces of immature mouse testes and transplanted them into the testes of host mice whose own sperm had been destroyed by an injection of a cancer drug to mimic damage done by cancer treatment. The transplanted tissue grew in the host mice, spermatogenesis (the process of sperm making) was restored and the tissue produced mature sperm. The researchers recovered spermatogenic cells from this tissue, refroze them and later injected the mature sperm into mouse eggs, transferring the resulting embryos into surrogate mice. A total of 62 mice were born from 123 embryos that successfully implanted. The donor origin of the mice could be confirmed by ultra-violet light as the donor parents were 'green' mice a breed containing jellyfish genes that glows green under ultra violet light.
In another experiment frozen pieces of rabbit testicle were transplanted into immunodeficient mice. Again spermatogenesis was restored in a high percentage and yielded mature rabbit sperm. The researchers injected sperm that developed from freshly transplanted tissue samples into rabbit eggs and transferred embryos into two su
Contact: Margaret Willson
European Society for Human Reproduction and Embryology