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Well, all the transhumanists should be very interested in this one:<br>
&lt;<a href="http://www.newscientist.com/news/news.jsp?id=ns99992677" eudora="autourl">http://www.newscientist.com/news/news.jsp?id=ns99992677</a>&gt;<br><br>
<blockquote type=cite class=cite cite>Cross-species testes transplant
successful </blockquote><br>
<blockquote type=cite class=cite cite>19:00 14 August 02 NewScientist.com
news service <br>
Testis tissue from goats and pigs has been grafted onto the backs of mice
and shown to produce normal sperm, capable of fertilising eggs. <br>
It is the first time testis tissue from such distant species has produced
mature sperm when grafted in mice. &quot;It might work for primates or
even humans,&quot; claims Ina Dobrinski of the University of
Pennsylvania, one of the co-authors of the study. <br>
If so, the technique could be used to preserve the reproductive potential
of male cancer patients about to undergo therapies that would destroy
their ability to make sperm.<br>
Men often freeze sperm samples before receiving chemotherapy, but young
boys cannot do this because they do not produce mature sperm. If it works
in humans, the technique would allow testis tissue grafted from boys to
mature and produce sperm.<br><br>
Infectious particles <br>
The mouse grafting technique also has an advantage over another option
for preserving fertility - testicular transplants. These involve
re-implanting preserved germ cells into the testes after cancer
remission. <br>
But the grafting approach &quot;would eliminate any possibility of
passing cancer cells back to the patient,&quot; says reproductive
biologist Michael Griswold from Washington State University.<br>
However, it is possible that the grafting procedure could introduce
mouse-derived infectious particles into human embryos, making some
scientists wary of the idea. &quot;I would very much hesitate to say that
it's something we should be doing,&quot; says reproductive biologist
Roger Gosden of the East Virginia Medical School.<br><br>
Castrated mice <br>
In the study, Dobrinski and colleagues placed small pieces of testis
tissue from newborn goats or pigs just under the skin on the backs of
castrated mice. Two to four weeks later, they found that more than half
of the 477 grafts had survived and were producing normal-looking goat or
pig sperm.<br>
When they injected the graft-derived sperm directly into eggs they saw
clear signs of fertilisation, indicating that the sperm function
normally. The researchers also found that the procedure worked just as
well with testis tissue that had been refrigerated for two days or frozen
for several weeks.<br>
Gosden has tried transplanting human testes tissue into mice, but was not
successful. However, Dobrinski believes the technique could soon be used
to preserve the germ lines of endangered species, including rare animals
that usually die in captivity before reaching sexual maturity. &quot;We
think that's a very real application,&quot; she says.<br>
She adds that mice with human testis tissue grafts would also be useful
to scientists who want to test the effects of toxic substances and new
contraceptives on human sperm production. <br>
Journal reference: <i>Nature</i> (vol 418, p 778) <br>
Robin Orwant</blockquote><br><br>
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