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Ethanol

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Ethanol

Postby bioquest » Wed Jun 22, 2005 8:40 am

Can somebody tell me why 70% ethanol is used as a fixative for biological tissue? Such as brain tissue. 70% ethanol is used as a fixative. Also, I have read that 30% EtOH can help instead of 70% if one is looking for astroglia. Any ideas why? Just a lesser strength fixative or has it got to do with dehydration?

Any help, even on the chemistry of EtOH or links to somewhere, will be hugely helpfull please.

Thanks
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Postby b_d_41501 » Wed Jun 22, 2005 2:07 pm

It probably has something to do with altering the shapes of the structures that you will be looking for.
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Postby victor » Thu Jun 23, 2005 8:56 am

I usually take a 96% ethyl alcohol instead of 70%.. :wink:
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Postby MrMistery » Thu Jun 23, 2005 8:21 pm

Actally it doesn't really matter if you use 70%, 60% or 50%. The 70% has been defined as optimal by experiments: it kills cells and leaves the membranes intact... at 96% you may have problems that it also disolves membrane proteins, put the probability is very small...
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Postby Beetle » Thu Jun 23, 2005 11:00 pm

I was told that for dna analysis (e.g. for dna taksonomy) is best 96% ethanol. Maybe it does not temper with dna structure. And from personal experience I know that 70% alcohol can dehidrate specimens (expecialy bigger organism like vertebratas) and that is better to use more diluted alcohol or to gradualy increse concetration.
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Postby Poison » Sat Jun 25, 2005 1:52 pm

They told us that gradually increasing concentration is the best way of dehydrating.
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Postby Beetle » Sat Jun 25, 2005 10:19 pm

Possibly. But maybe that method does not shrink specimens but just slowly switch water for alcohol.
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Postby victor » Mon Jun 27, 2005 6:46 am

:lol: ...so 96% is better than 70%.
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