isotropy by assessing corneocyte micromorphology, using SEM on tape-stripped skin samples from six subjects, whom we considered best responders based on clinical assessments. Similar to Fluhr et al., the skin surface isotropy was obtained by evaluating three corneocyte microstructural parameters: cellular clusters at magnification x50, dispersion at x250, and differentiated single cell appearance at x500 (Figure 3A).16 We found that the UV only zone tended to exhibit a lower SC surface isotropy compared to control at day 1 and day 14 after irradiation, indicating disruption of superficial SC barrier organization patterns (Figure 3A and 3B). At day 1 following UVR, the appearance of both regular clusters and well differentiated corneocytes were significantly reduced in UV only, which the latter tended to be prevented by SPF+Moisturizer routine. By day 14, treatment with SPF or SPF+Moisturizer routine significantly preserved the appearance of well differentiated cornecoytes comparable to control, while weakly differentiated cells persisted in UV only (Figure 3C and 3D). Together, these results suggest that the SPF+Moisturizer routine tended to be most effective in maintaining SC barrier morphological features after UV exposure.
