Refractive index measurement in human tissue samples

Abstract

The aim of this study was to apply a laser refractometer based on a total internal reflection for measurement of refractive indices of thin tissue samples. The tissue slices with thickness from 5 to 15 &mu;m and cross-sectional area of about 1 - 1.5 cm were cut with a freezing microtome and mounted on microscope glass slides. The samples from a liver, kidney, myocardium and skin were taken <i>post mortem</i> from 3 male patients (50, 52 and 75 years old) with some pathological tissue changes as well as from 3 dead fetuses 24-48 hours after the death. To indicate the morphological changes, the samples were stained with hemolown-eosin (HE) and studied microscopically. Using a two-beam UV-Vis-NIR-spectrophotometer Cary-5E (Variant), on-axis transmittance of the samples was measured over the 350 - 2000 nm range and the spectra of the extinction coefficient, in cm^-1, were calculated. The measured refractive indices correspond to dehydrated tissue samples.