help with PFA fixation

Ole Hartvig Mortensen ohm at
Wed Mar 28 04:13:05 EST 2001

> while I am well fixed tissue (rat-pup brain) for
> vibratome sectioning, 4% PFA fixation for
> immunohistochemistry is yielding poorly fixed tissue
> even with over night fixation.
> Could I
>        a. use 4% PFA in PBS instead of 4% PFA in
>            phosphate bufer.
>        b. increase the concentration of PFA as the
>           powder is quite old.

4 % PFA in PBS has worked fine for me. Wash the cells in cold PBS twice,
add 4 % PFA in PBS and let stand at room temperature for 30 minutes.
Pour off the PBS containing 4 % PFA, and add fresh cold PBS. Store at 4
degree celcius.
(hint: by not washing but just changing the media after PFA fixation, you'll
use the leftover PFA to avoid bacterial / fungal growth)



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