[Histonet] Trouble making a good Cell Block

[Monfils, Paul]

To make a cell block from formalin-fixed cells, you need to introduce some coagulable material that will stick the cells together.  Here's a method I have used successfully:

Spin down the cells in formalin, decant as much formalin as possible with a pipette.
Fill tube with isotonic buffer, resuspend cells, respin, decant as above.
Add about 1 ml of isotonic buffer, plus a few drops of coagulant. A concentrated solution of albumin or agar or gelatin can be used, or serum.  I'm sorry I don't have exact percentages for solutions.
Resuspend, respin, decant as above.
Gently add 1 ml of 70% ethanol.  Don't drop it directly on the pellet, but allow it to run slowly down the side of the tube.
Leave for 20 minutes to 1 hour depending on the size of the pellet.
Decant and replace with 95% ethanol, allow to stand as above, replace with absolute ethanol.
As the pellet is dehydrated it shrinks, just like any tissue, and usually detaches from the tube once dehydration is complete. Otherwise you can reach down and just touch the pellet with the tip of a probe and it will detach.  Then you can either complete hand processing in the tube, or remove the pellet for machine processing.