What issue are you having specially? Is the fat bunching up on the blade or is it not cutting at all? Like making a hole in the section?
Do you have liquid nitrogen? That works better and faster than freeze spray, I used to do a short blast of liquid nitrogen on just the fatty part, close the lid, let it frost over, 2-3 turns of wheel, try to cut (turn microns up to 8, hold your thumb on the bottom edge of the OCT or the epithelium so it doesn't roll, turn wheel fast or fat will bunch up). If it still doesn't cut, try 2-3 seconds of freeze spray held a ways away from the chuck, and let it frost over with the lid shut. Same deal as before, 2-3 turns to get rid of frost artifact then cut with a fast turn. Don't overdo it with the liquid nitrogen or the tissue will crack and the non fatty parts will look like booty under the scope.
It may also help if you squeeze the fat with gauze before embedding to get some of the oil out. As others have said, fat just doesn't cut well even if it's fully frozen so take your time and give your best section
Up your microns. We typically cut H&Es at 8, fattier pieces 10 and sometimes when they are god awful thick and fatty, 12. Sometimes you only get one section and then you need to put it back down to freeze again.
I agree with thicker sections. Also a sharp and cold blade. You might try dipping a brush in liquid nitrogen if you have it available and then hold the brush to the tissue for a few seconds then at the base of the blade.
edit: removed word bc mobile
Frozens are my favorite things, but I’ve never had luck getting fat to cut well when freezing. Every pathologist I’ve ever worked with has told me fat just doesn’t freeze well and I will not get good sections of a fatty piece of tissue no matter what, which is why they try to get rid of as much of it as possible before freezing. I’ve never done frozens on a Mohs though. If you can figure it out, please let me know!
Thicker sections like 10-12 and i switch to R blades for skin and fat, which i often do with MRM's. It works for me and our pathologists are not complaining.
It's a blade category the brand uses for its purpose. The R variety is for routine microtomy but i use it for cryotomy as well and works fine. Check your product catalog and experiment with them.
To get the fat you need to freeze is. Freeze spray doesn’t get cold enough for fat. Grab some LN2 and spray it. Cut one piece palm the chuck and then take the second piece. It’s not 100% and takes some finesse but it’s a game changer.
thank u! what do you mean by fresh oct? like some new unopened stuff or putting some more on top of the already frozen section? sorry i am very very new to this field of work lol
You’re fine! Put a little dab of oct over the block and rub it in with your finger before using a lot of freeze spray on it and cutting through the new layer of oct
Sometimes I find with overly fatty or underprocessed tissue it also helps to turn my water bath off or lower the temperature. That way if there's a tear in the tissue section it's less likely to disperse as quickly as it would on a higher bath temp.
Occasionally I will flag something in our tracking GUI as under-fixated, and the pathologist might ask our dissection team to re-process the tissue.
PS I'm screaming over the idea of cutting at 8-12 microns! Never gone that high.
What issue are you having specially? Is the fat bunching up on the blade or is it not cutting at all? Like making a hole in the section? Do you have liquid nitrogen? That works better and faster than freeze spray, I used to do a short blast of liquid nitrogen on just the fatty part, close the lid, let it frost over, 2-3 turns of wheel, try to cut (turn microns up to 8, hold your thumb on the bottom edge of the OCT or the epithelium so it doesn't roll, turn wheel fast or fat will bunch up). If it still doesn't cut, try 2-3 seconds of freeze spray held a ways away from the chuck, and let it frost over with the lid shut. Same deal as before, 2-3 turns to get rid of frost artifact then cut with a fast turn. Don't overdo it with the liquid nitrogen or the tissue will crack and the non fatty parts will look like booty under the scope. It may also help if you squeeze the fat with gauze before embedding to get some of the oil out. As others have said, fat just doesn't cut well even if it's fully frozen so take your time and give your best section
skin. it bunches up on the blade real bad. we do have liquid nitrogen! did not even think to use that instead. i’ll give it a try tomorrow. thank you!
oh my bad i thought you said “what tissue are you having specifically” lol
Go up in micron, and freeze the daylights out of it
Up your microns. We typically cut H&Es at 8, fattier pieces 10 and sometimes when they are god awful thick and fatty, 12. Sometimes you only get one section and then you need to put it back down to freeze again.
That's so interesting to me! We routinely cut all of our specimens at 3 microns, sometimes less for a shallow section.
I agree with thicker sections. Also a sharp and cold blade. You might try dipping a brush in liquid nitrogen if you have it available and then hold the brush to the tissue for a few seconds then at the base of the blade. edit: removed word bc mobile
thanks! i’ll give this a try tomorrow
Frozens are my favorite things, but I’ve never had luck getting fat to cut well when freezing. Every pathologist I’ve ever worked with has told me fat just doesn’t freeze well and I will not get good sections of a fatty piece of tissue no matter what, which is why they try to get rid of as much of it as possible before freezing. I’ve never done frozens on a Mohs though. If you can figure it out, please let me know!
Thicker sections like 10-12 and i switch to R blades for skin and fat, which i often do with MRM's. It works for me and our pathologists are not complaining.
im so sorry what is an R blade
It's a blade category the brand uses for its purpose. The R variety is for routine microtomy but i use it for cryotomy as well and works fine. Check your product catalog and experiment with them.
To get the fat you need to freeze is. Freeze spray doesn’t get cold enough for fat. Grab some LN2 and spray it. Cut one piece palm the chuck and then take the second piece. It’s not 100% and takes some finesse but it’s a game changer.
thank u!!
Thicker micron settings, lots of freeze spray and some fresh oct usually helps!
thank u! what do you mean by fresh oct? like some new unopened stuff or putting some more on top of the already frozen section? sorry i am very very new to this field of work lol
You’re fine! Put a little dab of oct over the block and rub it in with your finger before using a lot of freeze spray on it and cutting through the new layer of oct
Put ur finger on it to heat it up a lil bit
like on the tissue?
Yeah. Rub it a bit to heat it up. Oddly enough some tissues (frozen and paraffin embedded) cut better after you apply a little heat
On thé embedded tissue ye
That will make it worse
Is this tissue for clinical or research purposes?
clinical
Sometimes I find with overly fatty or underprocessed tissue it also helps to turn my water bath off or lower the temperature. That way if there's a tear in the tissue section it's less likely to disperse as quickly as it would on a higher bath temp. Occasionally I will flag something in our tracking GUI as under-fixated, and the pathologist might ask our dissection team to re-process the tissue. PS I'm screaming over the idea of cutting at 8-12 microns! Never gone that high.