Maybe helpful will be protocols of retina wholemount immunohistochemistry.

Here longer incubation times, higher concentration of detergents like Triton-X100 or even the use of DMSO is recommanded. This you have to check systematically.

If there is no need to investigate such thick sections I would recommand to cut them thinner. This could easily be done if you have a freezing microtome or a cryostate.

1. Put on the tissue holder a big blop of 30% sucrose. It should be bigger than your tissue section.

2. Waite until it is completely frozen

3. Cut it carfully plane

4. Mount your section on a coverglas

5. Mount the tissue upside down on the sucrose blop

6. After the tissue is frozen on the sucrose rub carfully with your finger over the coverglas, meld it a little bit and pull the coverglas horizontaly away, don't lift it up

7. Fix the tissue section with sucrose.

8. Start carefully with the sectioning.

9. Collect the thinner sections (30µm, 50µm or thicker) in 96-well microtiter plates, every well one section.

Now you have the choice to stain all sections or just few of them as you like.

You should do the immunohistochrmistry free floating and mount them afterwards on a slide because you will get a better and homogenous result as when you stain them dirctly on the slide.