PVA-G mountant

Here you can discuss sample and specimen preparation issues.
Post Reply
Message
Author
TonyT
Posts: 184
Joined: Fri Sep 11, 2020 8:30 pm
Location: New Brunswick, CANADA

PVA-G mountant

#1 Post by TonyT » Wed Mar 03, 2021 7:54 pm

I normally mount my insect preparations, mostly moth genitalia, in Canada Balsam. Very recently I have been using a PVA/glycerol mix.
Even more recently I have switched to the following recipe from an article in Micscape magazine:

"Some time ago I started to question why the PVA was restricted by professional microscopists to the lactophenol formulas (now additionally restricted to lactoglycerol formulas). So I tried with relative success the CPG adventure (see part 2). Now I propose you indulge in the heresy and design a PVA based media of mild clearing action, a lot less acidic, that could be of a more general application (including those little tardigrada, with his delicate calcified pieces). My own experimental version is below which I've put on the trial to monitor its behavior for the next few months."

PVA-G.- Polyvinyl Alcohol-Glycerol medium
O’Glue…………………10 ml
Borax Water*..……….…4 ml
Glycerol…………………6 ml
*Saturate water with granulated borax (>6 g of borax /100 ml water). Use the supernatant liquor.

http://www.microscopy-uk.org.uk/mag/ind ... art3b.html

Here is a genitalia prep. made today. Placed 1 drop of the mix on a slide, spread into a thin layer; let dry for 15 mins. to get it even more 'tacky'.
Added the genitalia from this moth, genitalia was in pure glycerin but could have been in water.
In a natural situation the two lateral valves meet in the midline hiding the other structures. The very tacky PVA-G mix allowed me to slightly spread apart the valves and for them to stay spread.

The length of the genitalia is 1.30 mm, photographed at at about 7x using a reversed 28mm on bellows with a Nikon D7200 camera.
Images of the moth, a male, and its genitalia.
Attachments
1046 moth.jpg
1046 moth.jpg (44.61 KiB) Viewed 2002 times
1046 gen.jpg
1046 gen.jpg (89.2 KiB) Viewed 2002 times
New Brunswick
Canada

viktor j nilsson
Posts: 760
Joined: Thu Aug 23, 2018 10:12 pm
Location: Lund, Sweden

Re: PVA-G mountant

#2 Post by viktor j nilsson » Wed Mar 03, 2021 8:28 pm

Now that looks very nice and convenient.

I would however, be a little hesitant to use this for permanent slides with specimens of potential taxonomic value. Are you planning on donating your collection to a natural history museum eventually? I will donate my fly collection when that time comes, and I therefore want to think that any genital preps should last hundreds of years. What do you think of the longevity of these mounts? To me, Euparal seem like a safe bet, and quite pleasant to use.

MicroBob
Posts: 3154
Joined: Sun Dec 25, 2016 9:11 am
Location: Northern Germany

Re: PVA-G mountant

#3 Post by MicroBob » Thu Mar 04, 2021 7:17 am

Hi Tony,
that mount looks very good! It is probably not easy to get the orientation right every time.

When looking for long lasting mountants there is a very interesting article: https://opus4.kobv.de/opus4-bam/files/42332/Zootaxa.pdf

Bob

TonyT
Posts: 184
Joined: Fri Sep 11, 2020 8:30 pm
Location: New Brunswick, CANADA

Re: PVA-G mountant

#4 Post by TonyT » Thu Mar 04, 2021 3:35 pm

Thanks Victor: I believe the PVA medium is a good place to start for beginners. I use it as a temporary mount to check genitalia; anything new or interesting gets permanently mounted in Canada Balsam.
Thanks Bob: great reference, a lot to digest, 173 pages! I'm still waiting for the package.
New Brunswick
Canada

pippo1234
Posts: 81
Joined: Thu Dec 24, 2020 8:21 am

Re: PVA-G mountant

#5 Post by pippo1234 » Fri Mar 05, 2021 2:23 pm

Hi Tony,

they look very nice. I too am a fan of PVA-G.

Bob, that "article" (in my discipline no journal would accept anything that long!) is exactly what I was looking for! Thanks.

Post Reply