Epidermal thickness measured by light microscopy: a methodological study

Publisher Website
Google Scholar
Abstract
Epidermal thickness is frequently measured by light microscopy. The preservation and staining methods may alter the proportions of the specimens and thereby influence the measurements. The aim of the present study was to describe: 1) a standardized light microscopic method to quantify the thicknesses of the stratum corneum and the cellular epidermal layers, 2) the variations according to preparation and staining techniques, and 3) the observer variability. One hundred and sixty skin biopsies from 67 human volunteers were included. The cellular epidermis and the stratum corneum were estimated in sections preserved by freezing and subsequent preparation with cryostat or formalin-paraffin techniques. The slides were stained with haematoxylin-eosin or er-ythrocin, and thicknesses of the stratum corneum and the cellular epidermis were measured by a calibrated ruler and an ocular grid, respectively. The formalin fixation gave slightly higher values for the cellular epidermis than the cryostat technique. In comparison to erythrocin staining, haematoxylin-eosin gave a significantly thinner stratum corneum. No significant inter- or intra-observer variation was found for the thickness of the stratum corneum assessed twice by two experienced observers. However, the two observers differed slightly from each other on the thickness of the cellular epidermis. It is found that thickness measurements of the stratum corneum and the cellular epidermis are reliably performed on cryostatic cut sections stained with haematoxylin-eosin.