“…The AgNOR technique has been Aging Effects on Mouse Tongue Epithelium used for over 20 years and, as such, its relationship with cell proliferation rate is well established 2,5,8,[10][11][12]14,18,20,21,23) . Çelenligil-Nazliel et al 4) and Sakai et al 15) used PCNA and BrdU, respectively, which are markers that are directly related to cell proliferation expressed during the interphase. The AgNOR technique has an advantage over other proliferation markers such as Ki-67, PCNA, tritiated thymidine and BrdU, since it provides information about cell proliferation rate, i.e., cell doubling time, whereas the other proliferation markers mentioned indicate whether cells are dividing or not, i.e., the growth fraction 10,11) .…”