fixation of tissues using 4% paraformaldehyde

I am fixing rat ovary using 4% paraformaldehye for IHC.tissues are not intact but nick and crack appears around the tissues  on sectioning.what exact steps and timings should i follow.pls help

 Hi,
the fixation time depends on thickness of your tissue, for rat ovary overnight would be enough also check the pH of PFA , clarify how you are processing your tissue after fixation means are you going for cryosectioning or paraffin sectioning if cryo then are you going for cryoprotection in 30 % sucrose befoere sectioning.............elaborate your querry for further help

thank u pundir. the ovary size is about 3cm x 3cm, PFA of pH7.4, and tissue processed in paraffin.tissue fixed for 72 hours as tissue doesnt get fixed in 24 or 48 hrs.fixed tissue are processed as follows: PBS 1x wash - 3x -30 min each dehydration in alcohol series of 30%,50% -30 min each, 70% -overnight, 90%,100% -30 min each, 100%:xylene-20min xylene I & II -20 min each Xylene : wax - 45 min wax I & II - 45 min each wax III - 1 hr embedding

hai
can any body tell me 4% paraformaldehyde and 10% formalin is same or different

thanks

Hello,

I hope you solve your doubts.
Anyway, 4% formalin and 10% formalin is the same, as it comes from 35-37'5% and you could consider it as 4% (37%) or 10% if you add 9 times solvent.
Paraformaldehyde is the polymer and you can consider it in the same way. You will use PFA when the fixation concentration is critical.

Good luck,

Pedro