Sensitivity of the electron spin resonance technique as applied in histochemical research on normal and pathological calcified tissues.

Abstract

The electron spin resonance (ESR) technique is proposed as a microchemical and/or histochemical method in research on mineralized tissues. It has been described in previous papers that ionizing radiation evokes stable paramagnetic centres in the crystalline fraction of mineral constituents of calcified tissues. These centres were used as a label in studies on resorption and creeping substitution of bone grafts. In this paper the sensitivity of the method and its application for determination of the crystallinity of various mammalian tissues were described. It was shown that: a) three single Haversian systems (osteons) isolated from a ca. 100 μm thick undecalcified section of human compact bone weighing around 10−4 g could be measured by the ESR technique; b) the crystallinity of mineral constituents of normal and pathological calcified tissues could be estimated as the ratio of the concentration of stable paramagnetic centres to the total ash content. Comparative ESR measurements were performed on compact bone of various mammalian species, human enamel and dentin, as well as on ageing bovine cartilage and atherosclerotic human aortas.