Elemental distribution in guinea-pig skin as revealed by X-ray microanalysis in the scanning transmission microscope

Abstract

Skin from the back of guinea pigs was prepared for x-ray microanalysis by rapid freezing and cryosectioning; sufficient ultrastructural detail could be seen in the STEM-mode without staining. X-ray microanalysis in the electron microscope showed the sulfur concentration to be highest in the stratum corneum and to decrease towards the stratum germinativum. The phosphorus concentration was very low in the stratum corneum, increased sharply in the stratum granulosum and remained at a high level throughout the rest of the epidermis. The distribution of potassium followed that of phosphorus. The sodium level was low in the stratum corneum and increased sharply in the stratum granulosum. The potassium to sodium ratio was highest in the stratum germinativum. The calcium and magnesium levels in the epidermis were low. Our results show the existence of marked concentration gradients for many elements in the skin. X-ray microanalysis is a method which can be applied to the study of shifts in the concentrations of physiologically important elements in the different strata of mammalian skin.