Thanks for the suggestions.
I did not realize the age of the tissue might be a factor. I
came across the problem when using younger
tissue - 12 days old. This age, of course, is also
harder to perfuse. With the possibility of fixation variance - are
there any controls commonly used to compare fixation from different tissues.
Here a little more of my proceedure
Fixation - 4% Para, intracardial
Post fixed - 12-48 hours
sucrose sink - 3-5 days
solution - All 0.1 M PBS (exept of the DAB reaction which is TBS)
storage - O.1 PBS with Sodium Azide
The paint brush is a good idea, but once the tissue sticks it would
not be enough to separate the sections. One other suggestion I may
try is using a holder with a mesh bottom, making the transfer of solutions
I'm open to any other ideas, specially about fixation controls (no Freudian jokes