Mean foreskin keratin thicknesses by donor and region.

<p>(A) Representative image of intra-individual variation in keratin thickness (outer foreskin). White ‘<b>⁁⁁⁁</b>’ symbols show areas of thinner keratin and white solid triangles show areas of thicker keratin. Involucrin (green), filaggrin (red), cell nuclei (blue). Inset: magnification of boxed area with only filaggrin staining (red) shown; scale depicts thickness in microns. (B) Illustration of foreskin regions examined: inner (red), frenar band (yellow), and outer (green) foreskin. Whisker and boxplots of individual keratin measurements demonstrating distribution of thicknesses. Median = middle line, box = 25–75^th percentiles, whiskers = 5–95^th percentiles, mean = ‘+’ symbols, outliers not shown for ease of viewing. *<i>p</i><0.05, **<i>p</i><0.001. (C) Correlation of mean regional measurement per donor. Each symbol represents mean thickness calculated for one donor. Light gray boxes/line = inner: frenar band ratio and dark gray circles/line = inner: outer ratios.