Stereological estimation of epidermal volumes and dermo-epidermal surface area in normal skin.

Quantitative morphological studies of the healthy epidermis are essential in providing a range of parameter estimates that can be considered within the range of normality. Stereology is a set of statistical tools that provides potentially unbiased and precise estimates of 3-dimensional tissue characteristics from 2-dimensional sections. We set out to establish reference values for the volume of the viable epidermis contained within a four-millimetre punch biopsy (V(epi)), the volume of the stratum corneum (V(SC)) and the surface area of the dermo-epidermal junction(A(DEJ)) in 4 predetermined body regions by use of stereology. Four-millimetre punch biopsies were taken from 20 freshly diseased corpses, fixed in formalin and embedded in paraffin. V(epi), V(SC) and A(DEJ) were established stereologically for all 4 body locations followed by pairwise comparison of means after Bonferroni correction. V(epi) was significantly larger in the sole compared to all other body locations (p < 0.01). Furthermore, linear regression analysis showed a strong linear relationship between V(epi) and V(SC) in the sole (r = 0.70). Our results suggest that the viable layers of the epidermis might also serve a mechanical function, either directly or by providing the stratum corneum with keratinocytes to support the hyperkeratosis in the weight-bearing parts of the skin.