beta-gal senescence staining of mouse tissue

[AS]

Hi,

I am planning to do immunohistochemistry with embryonic / adult KO
mouse tissue to look for signs of senescence  by X-Gal staining (kit
from Cell Signaling Tech). Do you think these tissue should be
formalin/paraffin embeded or snap frozen? Also can these tissues be
collected for a couple of weeks and then stained?

Thanks for your comments
Tony