[Nhcoll-l] [EXTERN] Re: Best practices for ethanol-fixed specimens

Fri Apr 24 01:38:55 EDT 2026

... and that "once they are stable in 95%", but osmotic damage is done (which usually is irreversible and includes cell rupture, which makes the specimens less suited for histology and analysis of fine cell structures, embryos tend to be used for).

With best wishes
Dirk

Am 23.04.2026 um 23:35 schrieb Simon Moore:
ACHTUNG/ATTENTION: Diese E-Mail stammt von einem externen Absender. / This e-mail comes from an external sender.

Hi Beth,

Remember that EtOH is only a pseudo-fixative as it doesn’t really bring about a chemical change.
Sorry to be such a pedant!

With all good wishes, Simon

Simon Moore MIScT, RSci, FLS, ACR
Conservator of Natural Sciences and Cutlery Historian.

www.natural-history-conservation.com<http://www.natural-history-conservation.com>

[cid:part1.mjZQWYDj.VTRY1MSz at leibniz-lib.de]

> On 23 Apr 2026, at 21:30, Elizabeth Wommack <ewommack at uwyo.edu><mailto:ewommack at uwyo.edu> wrote:
>
> Hi Verity,
>
> One thing you could do is check to see if they have finished fixing in the 95% ETOH. Check to see if the concentration of the ETOH they are in is 95%. If it is less then they may still be exchanging water with the preservative, and you might want to put them in some fresh 95% ETOH for a bit longer. Once they are stable at 95% ETOH, I switch ETOH fixed material to 70% ETOH for long-term storage.
>
> cheers,
> Beth
>
> Elizabeth Wommack, PhD
> Curator and Collections Manager of Vertebrates
> University of Wyoming Museum of Vertebrates
> Berry Biodiversity Conservation Center
> University of Wyoming,
> Laramie, WY 82071
> ewommack at uwyo.edu<mailto:ewommack at uwyo.edu>
> pronouns: she, her, herself
> www.uwymv.org<http://www.uwymv.org>
> UWYMV Collection Use PolicyFrom: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu><mailto:nhcoll-l-bounces at mailman.yale.edu> on behalf of Dirk Neumann <d.neumann at leibniz-lib.de><mailto:d.neumann at leibniz-lib.de>
> Sent: Thursday, April 23, 2026 00:09
> To: nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu> <nhcoll-l at mailman.yale.edu><mailto:nhcoll-l at mailman.yale.edu>
> Subject: Re: [Nhcoll-l] [EXTERN] Re: Best practices for ethanol-fixed specimens
>  ◆ This message was sent from a non-UWYO address. Please exercise caution when clicking links or opening attachments from external sources.
>
> Hi Verity,
>
> I would opt for 70%; 95% not only strongly dehydrates the specimens, but also causes a lot of osmotic pressure on tissue membranes, which might effect the usefulness of the specimens for morphological analysis. Tissue subsampling and subsequent storage of tissues in 95% for later molecular investigation might be better.
>
> Hope this helps
> Dirk
>
>
> Am 22.04.2026 um 22:50 schrieb Shoobs, Nate:
>>
>>
>> Depends on what you want to use them for!
>> Formalin is not a great long-term preservative, even though it's a great fixative. Since the tissue is fixed already, unless you want to post-fix for some specific purpose like histology, I'd leave them in ethanol.
>> It's fine to keep things in 95% indefinitely, but if you think they will be used mainly for anatomical study, swapping the 95% for 70-75%  is better for long term storage and will keep the tissues flexible. Some institutions use 80% as a compromise between genetic and anatomical preservation. If you typically voucher frozen material, I'd recommend taking your tissue samples and freezing them before stepping the lot(s) down in concentration. You could even chuck a whole individual in 95% into the freezer.
>>
>> Personally, I rarely if ever use graded ethanol series for going from high to lower concentration, especially for fresher material, I only bother when going from low-high, but I'm unsure how vertebrates typically handle.
>> My 2 cents!
>> -Nate
>> --<image001[26].png>
>>
>> Nathaniel F. Shoobs
>> Curator of Mollusks
>> College of Arts & Sciences Dept. of Evolution, Ecology, and Organismal Biology
>> Museum of Biological Diversity, 1315 Kinnear Rd, Columbus, OH 43212
>> 614-688-1342 (Office)
>> mbd.osu.edu/collections/invertebrates
>> From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu><mailto:nhcoll-l-bounces at mailman.yale.edu> on behalf of Mathis,Verity L <vmathis at flmnh.ufl.edu><mailto:vmathis at flmnh.ufl.edu>
>> Date: Wednesday, April 22, 2026 at 4:38 PM
>> To: nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu> <nhcoll-l at mailman.yale.edu><mailto:nhcoll-l at mailman.yale.edu>
>> Subject: [Nhcoll-l] Best practices for ethanol-fixed specimens
>>
>> This Message Is From an External Sender
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>>  Hello all
>> I am hoping to get feedback on the best practices for some recently fixed fluid specimens.  During some recent field work, our lab fixed some rodent fetuses in 95% ethanol while prepping.  I’m hoping for some advice on how best store them long-term now that they are back in the lab/collections.  Do I keep them in 95% ETOH, re-fix them in formalin, or step them down to 70% ETOH for long-term storage?  Or something else altogether?
>>  Thanks for any insight!
>> Verity
>> ******************************
>> Verity L. Mathis, Ph.D.
>> Mammal Collections Manager
>> Florida Museum of Natural History
>> University of Florida
>> 1659 Museum Road
>> Gainesville FL 32611
>> Phone: (352) 273-2114
>> Email: vmathis at flmnh.ufl.edu<mailto:vmathis at flmnh.ufl.edu>
>> Website: https://www.floridamuseum.ufl.edu/mammals/
>> FM Mammal Collection Google Scholar: https://tinyurl.com/flmnh-mammals
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>
> --
> ****
>  Dirk Neumann
> Collection Manager, Hamburg
>  Postal address:
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> Dirk Neumann
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> --
> Stiftung Leibniz-Institut zur Analyse des Biodiversitätswandels
> Postanschrift: Adenauerallee 127, 53113 Bonn, Germany
>
> Stiftung des öffentlichen Rechts;
> Generaldirektion: Prof. Dr. Bernhard Misof (Generaldirektor), Adrian Grüter (Kaufm. Geschäftsführer)
> Sitz der Stiftung: Adenauerallee 160 in Bonn
> Vorsitzender des Stiftungsrates: Dr. Michael H. Wappelhorst
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> _______________________________________________
> NHCOLL-L is brought to you by the Society for the Preservation of
> Natural History Collections (SPNHC), an international society whose
> mission is to improve the preservation, conservation and management of
> natural history collections to ensure their continuing value to
> society. See http://www.spnhc.org for membership information.
> Advertising on NH-COLL-L is inappropriate.

--
****

Dirk Neumann
Collection Manager, Hamburg

Postal address:
Museum of Nature Hamburg
Leibniz Institute for the Analysis
of Biodiversity Change
Dirk Neumann
Martin-Luther-King-Platz 3
20146 Hamburg
+49 40 238 317 – 628
d.neumann at leibniz-lib.de<mailto:d.neumann at leibniz-lib.de>
www.leibniz-lib.de<imap://dneumann@webmail.leibniz-lib.de:993/fetch%3EUID%3E/INBOX/Privat/www.leibniz-lib.de>

--
Stiftung Leibniz-Institut zur Analyse des Biodiversitätswandels
Postanschrift: Adenauerallee 127, 53113 Bonn, Germany

Stiftung des öffentlichen Rechts;
Generaldirektion: Prof. Dr. Bernhard Misof (Generaldirektor), Adrian Grüter (Kaufm. Geschäftsführer)
Sitz der Stiftung: Adenauerallee 160 in Bonn
Vorsitzender des Stiftungsrates: Dr. Michael Wappelhorst

--
Stiftung Leibniz-Institut zur Analyse des Biodiversitätswandels
Postanschrift: Adenauerallee 127, 53113 Bonn, Germany

Stiftung des öffentlichen Rechts;
Generaldirektion: Prof. Dr. Bernhard Misof (Generaldirektor), Adrian Grüter (Kaufm. Geschäftsführer)
Sitz der Stiftung: Adenauerallee 160 in Bonn
Vorsitzender des Stiftungsrates: Dr. Michael H. Wappelhorst
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