June 4, 2023


Hey everyone welcome back to part two of this very interesting case this is uh the little piece of bone the little piece of dead mastoid bone or bony sequestrum underneath the compound microscope at times 40 magnification i think and as you can see it looks unusual but it could be dead skin and that’s what we wanted to verify so what we decided to do was uh immerse

This little piece of bone in potassium hydroxide or koh so k being the chemical sign for potassium and oh is the hydroxyl group uh 10 and what this does is it will lyse or dissolve skin basically so normally a koh test is for checking fungal infections so if you’ve had a case of ringworm or a suspected fungal infection somewhere on your body your doctor might take

Skin scrapings with a you know a dull scalpel um and those skin scrapings will then go onto a microscope slide with potassium hydroxide after some time it will dissolve all of the skin and then the doctor or lab technician or pathologist or whoever can look into the microscope and all of the skin will be lysed will be dissolved but the fungal cells will remain and

We’ve done we’ve shown that before on the channel it is really really fascinating the fungus often looks beautiful uh underneath the microscope so i’ll link that down in the description box below where we um where we did a koh test to identify a case of otomycosis which is a fungal ear infection but this is what it looks like after two days immersed in this little

Test tube of potassium hydroxide so if it was just a little clump of dead skin um it would all just you know even after you know five hours probably it would have just dissolved into nothing it would have been mush but here we can see it’s a nice white piece of bone these little crystals here are um the potassium hydroxide dried on the slide and it’s left behind

These beautiful crystals here so rather fascinating and this is the piece of bone again if you’re wondering why it looks different and it looks kind of broken up into segments i thought i would be clever and try and fish it out with crocodile forceps and that just broke it basically so that was unfortunate but um here we’re looking at it in a standard light field

Microscopy and all right now we’re looking at a dark field and uh i decided to stain it blue not for any particular scientific reason i just thought it would look nice and increase the contrast and i think what i’ve used here is games is stain not that it needed game sustained i could have stained it with fountain pen ink something like that but i often find that

When you stain things um because you increase the contrast it’s nicer or easier to look at at very very high magnification so i think this is times 100 maybe something like that um but absolutely beautiful specimen so there we go it is it is bone it is a bony sequestrum presumably uh it is delaminated from the substrate a healthy tissue underneath due to infection

And the infection would have caused a compromise in the blood supply of the bone so there we go i will leave you with a little bit more of this footage i hope you enjoyed it and of course if you have any questions leave them down in the comments section below and i will try my very best to get back to you thanks for watching good foreign foreign foreign foreign foreign

Transcribed from video
Mastoid Bone Under Microscope (Potassium Hydroxide KOH) By Durham Hearing Specialists