On Thu, 28 Sep 2000, Jean Edwards wrote:
> Three questions for which I've been unable to find answers:
>
> 1. How long can sperm remain frozen without comprising
> viability?
>2. Can ova be frozen and again, for how long
> without comprising viability?
>3. Finally, one of my students
> was talking with me about the thawing of the "ice man" who is
> estimated to be about 5000 years old. She was wondering if
> his sperm were retrieved and thawed and fertilized with an
> ova, would fertilization be possible and what would the brain
> be like? I told her that to the best of my knowledge, the
> brain had not changed that much in the last 5000 years and
> that I didn't know how long sperm could be frozen.
I thought these were imaginative questions so I gave them a shot.
There are quite a few commercial web sites for frozen sperm and
embryos (it's big business---a sign of the times!), and browsing
them gave me the following results:
1) The Virgina Mason Fertility Center says "It is still not known
how long sperm can be stored in liquid nitrogen temperature and
still be able to fertilize a human egg, but human sperm frozen
for as long as 19 years has caused conception."
2) It appears that ova can be frozen and remain viable. This
technique seems uncommon, though, as I found few mentions of it
on the web, compared with quite a few sites concerned with frozen
embryos. I think the reason may be that frozen ova don't preserve
as well as frozen embryos. In my quick search, I couldn't find
any information on how long they last after freezing.
3) Well, it's a fascinating idea, but it's a long way from the 19
years that's been demonstrated for frozen human sperm to 5000
years. Also, the 19 year sperm would have been stored in liquid
nitrogen which at -160 deg C (-320 F) would have done a much
better job of preserving the sperm than Otzi's glacier. That's
even colder than a day in winter in Quebec! So I'd say, no way
that this could be possible. Perhaps your student might want to
consider whether her question could be answered instead by
cloning Otzi from a surviving bit of his DNA. Now that, in theory
at least, might just be possible.
Of course, you might want to raise the question of the ethics of
doing either one of these experiments. Somehow, I suspect an IRB
would have some doubts. :-)
-Stephen
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Stephen Black, Ph.D. tel: (819) 822-9600 ext 2470
Department of Psychology fax: (819) 822-9661
Bishop's University e-mail: [EMAIL PROTECTED]
Lennoxville, QC
J1M 1Z7
Canada Department web page at http://www.ubishops.ca/ccc/div/soc/psy
Check out TIPS listserv for teachers of psychology at:
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