RATES OF CLEARANCE OF THE EPITHELIAL SURFACES OF MOUSE ORAL-MUCOSA AND SKIN

Cell desquamation, by removing material adherent to the epithelial sur face, appears to play an important role in limiting bacterial coloniza tion of epithelia. Data are available concerning rates of epidermal su rface clearance but similar data for oral mucosal epithelia, which exi st in an environment more conducive to colonization, have not been rep orted. The rates of surface clearance of six regions of murine oral mu cosa and skin were assessed by two different methods: (a) EM autoradio graphy to examine the rate of passage of a H-3-histidine label through the stratum corneum, and (b) measurement of rates of cell proliferati on and of the size of the superficial cells of the stratum corneum. Th e autoradiographic (direct) method indicated regionally-varying epider mal clearance rates (6.3-15.9 h) which compared well with published da ta. This method indicated considerably faster (2.3-3.4 h) clearance ra tes for the three oral mucosal regions. The rates of surface clearance that were calculated indirectly, from rates of cell proliferation and of cell size, similarly showed faster clearance rates for mucosa (2.0 -3.9 h) than for skin (6.0-17.9 h) but differed in the relative rates calculated for the individual regions of mucosa and skin.