i am afraid you may not be using the best approach.

isolate tissue, rinse of course

fix with fresh 4% PFA (fresh PFA frozen at -20 and thawed ((less than 5-7 day old) is equally good

try fixing for 10 min, 30 min, 1h at room temp

wash 3 times 10-20 min each in PBs, using a shaker is better

cryoprtotect in 10% sucrose/PBS for 10 min

then add equal vol of 20% sucrose (to make it 20% weight/vol)

after 30 min to 1h remove 20%, and add 30% sucrose on PBS, keep until the tissue sinks to the bottom of whatever you use (flask, tube etc)

put tissue in cryomold (there are different shapes, if you need a long one, make it from a pierce of foil), add OCT, keep some 30% sucrose (about 20-25% v/v)

let tissue stay in OCT for 15 min or so

snap freeze in dry ice/100% ethanol bath, make sure you keep cryomold above ethanol surface or you will get a lot of bubbles made out of OCT (some do it in isopentane/dry ice and then add OCT, it does not work well for small tissue but works for brain)

keep at -80 until use

when cutting, optimize the thickness, for small fine pieces like villi you need 10-12 micron tissue. Optimize temperature inside cryostat, it impacts sectioning

if you plan to do H&E, postfix you frozen (well, lightly PFA-fixed) tissue with 0.1% glut/4%PFA, and maybe Bouin fixative, otherwise tissue falls apart (this is where one of your problems is)

i recommend avoiding H&E (it destroys tissue sometimes), and instead add a drop of CV (cresyl violet) for some 15-30sec, then wash with PBS, coverslip and image. This is more gentle stain for fragile tissue. However the bulk of fragility is caused, in your case, by no fixation at the beginning, and no postfixing before H&E.

if you are concerned about IHCs and impact of fixative on antibodies - it works, and you can do gentle antigen retrieval even on frozen tissue. PFA is a partially reversible fixative. Good luck

I probably have more questions than answers, but maybe they can improve your protocol.

Are you perfusing when you sacrifice the animal?

Is there are particular reason you are avoiding formalin fixation?

Would you be better served by FFPE to get more/thinner sections? The harder media can help support smaller tissue structures.

It has also been pointed out that OCT tends to 'rubberize' when kept at -80C, that my be leading to your stiffness during cryosectioning.

Dear, Michał Chołko i think you should try this method, recently i used this method for brain sectioning.

After perfusion, brains were quickly dissected out and collected in 50 ml falcon tube (Tarsons) filled with 20 ml same fixative for overnight post-fixation. In next day, they were cryoprotected by immersing brains at 4 degree C for 4 hrs in 10% overnight in 20% and then 30% of sucrose (Marck) solutions still brain not drawn then brain store in 15% PVP till sectioning.