Old prepared slides vs new slides

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neal Shields
Posts: 58
Joined: Sat Jun 04, 2022 8:02 pm

Old prepared slides vs new slides

#1 Post by neal Shields » Tue Jul 19, 2022 9:29 pm

Old pig slide https://www.flickr.com/photos/196001110 ... ed-public/
New expensive pig slide https://www.flickr.com/photos/196001110 ... ed-public/

Old slides vs New slides.

For quite a while I have lusted after a set of slides by a large biological slide supplier. They are a serial section of an 8 - 10mm Pig embryo from the tip of his toes to the top of his head. Imagine my joy when I found a like new set for sale online for 25% of the normal price. You can buy a Chinese student microscope for the full price of these slides. I jumped at it.

When I got them in, I thought my microscope was broken! (BX50 with UplanFl objectives). Mud, mud and more mud!
I tried bright field, Phase, DCI... no joy.

I already had a single slide with 4 sections that was probably made in the '50s, but this set is 10 slides with about 36 sections per slide.

I checked the old slide and it was as clear as a bell (at least my microscope wasn't broken.)

The new slides aren't dirty, no caked immersion oil, they are as they came from the lab.

You can't tell from the picture but I think the main difference is that the old slide specimen is about an about 10 μm thick and the new section is several times that.

You can see several layers of cells in the new slides.

They have microtomes now (for scanning electron microscopy) that can cut slices down to the 50 nano meter range. I just can't understand why anyone would go through all the trouble to make a slide and not spend a little more time to get it right.

The problem may be two fold, the specimen is too thick and I think there is a thick layer of mounting medium above the tissue. (even the top layer won't snap into focus)

I think on the old slide they put the tissue on the coverslip and then put the coverslip with the tissue onto the slide.

The frustrating thing is, if the sample is as thick as I think it is, they could have made at least another set of slides with the same specimen!

It brakes my heart that some little pig gave his life for such poor quality.

Neal

neal Shields
Posts: 58
Joined: Sat Jun 04, 2022 8:02 pm

Re: Old prepared slides vs new slides

#2 Post by neal Shields » Tue Jul 19, 2022 9:31 pm

OOPS!

This is the new slide photo.

Sorry

Looks like the quality of my posting is up to the quality of the slide manufacturer.

https://www.flickr.com/photos/196001110 ... ed-public/

apochronaut
Posts: 6272
Joined: Fri May 15, 2015 12:15 am

Re: Old prepared slides vs new slides

#3 Post by apochronaut » Tue Jul 19, 2022 9:54 pm

It is a common problem. Thick and contaminated mountant, ungraded covers, simple undifferentiated stains. You can get better slides out of India and likely China too but they are hard to find and will be more expensive. I have some Indian slides that are quite good.
I think that most of the cheapness of the cheap slides gets overlooked because they are targeted at schools and intended to be used with .65 objectives or less. If you are going over that, as you say. Mud.

AntoniScott
Posts: 108
Joined: Tue Dec 24, 2019 3:54 pm

Re: Old prepared slides vs new slides

#4 Post by AntoniScott » Thu Aug 04, 2022 12:00 am

Old slides usually suffer from yellowing and cracking of the mounting medium, which is usually Canada Balsam. In some cases, you can find perfect slides from the late 1800's early 1900's but my experience was that it was a rare case. The round cover slips are many times, ringed, with a black paint like material which prevents the mountant from cracking due to solvent evaporation. The Canada Balsam can still yellow.
In 1958, I had a set of slides from some professional slide maker from London,probably made in the late 1890's. I know that because some of the slides were volcanic ash from the 1880's Krakatoa volcanic eruption. I've also seen dozens of slides from the 1950's and 1960's that were all yellowed and cracking 60 years later. That being said, I still enjoy looking at 100 year old slides.

Recent mounting materials, like Fisher's Permount, remain clear for years. I haven't seen any yellowing but I have seen cracking on the slide edges. Only time will tell how good Permount turns out to be.

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

Re: Old prepared slides vs new slides

#5 Post by MicroBob » Thu Aug 04, 2022 6:08 am

Hi Neal,
you might try to restore the slides by dissolving the mountant in xylene and mount the specimens new with proper cover slips, thin layer of clean mountant. But it won't be easy to get the specimen in place withut tearing or folding it.
They may make them this way to save time. Slicing them thick might allow to process them without mounting them on slides and this could speed up the process quite a bit. From what I hear they don't use microscopes a lot at universities in their zoology classes any more. So the slides might be aimed towards schools which would buy them and put them in a cupboard, where quality doesn't matter.

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