[Histonet] Long term museum specimen storage

[John Kiernan]

I don't know anything about "Jore's fixative" or the rationale of using a very hypertonic unbuffered 4% formaldehyde with magnesium, sodium, chloride and sulphate ions. If brown stuff is now bleeding out of your museum specimens, Jore Juice evidently isn't a good preservative.

According to Chapter 26 in the late Charles Culling's excellent book (3rd edn 1974; ISBN: 0407729011) the fixative/preservative for a museum specimen is optimized to preserve colour, which is the red or reddish-brown of haemoglobin and myoglobin. This usually is achieved with Kaiserling's fluid, which contains formalin, potassium acetate and also potassium nitrate (1.5% w/v) as an oxidant. Another approach involves treating specimens with carbon monoxide to convert all haemoglobin etc to a red carboxy derivative.

If your museum specimens have already lost all their meaningful colours, a neutral buffered aqueous formaldehyde may be the best that you can provide to preserve the sizes and shapes. 70% alcohol will cause some shrinkage, and it may not be as easy to seal this solvent into a museum container as a watery diluted formalin.

John Kiernan
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________________________________
From: Rhonda McCormick via Histonet <histonet at lists.utsouthwestern.edu>
Sent: September 20, 2023 11:39 AM
To: Histonet <histonet at lists.utsouthwestern.edu>
Subject: [Histonet] Long term museum specimen storage

Hi All,
I am looking to replace the fixative for veterinary specimens that have been preserved as "museum specimens". They are kept in jars in a glass case outside our lab, however, some of the fixative is starting to turn brown (and we've pulled a few jars that have some slight cracks in them).
The specimens are currently in Jore's Fixative: 100 mL Distilled water
10 mL 40% Formaldehyde2 g Magnesium Sulfate2 g Sodium Sulfate1 g Sodium Chloride
Preserving specimens is new to me. I've never heard of Jore's fixative before and I'm wondering if I could get some advice, please?  Do these specimens need to be replaced with the same solution? Could we rinse the specimen and replace the solution with 70% Alcohol? OR would 10% NBF be better to store the specimens in (or something al together different)? We have a varying display of specimens - anywhere from a small porcine optic nerve to a large equine granulosa cell tumor. Realizing it may be different based on the size of the specimen, approximately how often should the solution be changed ?
Thank you so much! Any help or insight is much appreciated.
Rhonda McCormickRhonda McCormick BS, HT (ASCP)cm
Histology Diagnostic Lab Supervisor

College of Veterinary Medicine
Texas A&M University

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