On the methodology of the thyroid epithelial cell thickness determination.

Abstract

SUMMARYThe average thickness of the thyroid epithelial cells may be determined either directly or indirectly. By the direct or caliper method, this thickness is overestimated as a result of which its empirical value must be divided by a correction factor Kd. By the indirect method, on the other hand, the thickness of the thyroid gland epithelium is calculated as the ratio of the double volume density of the epithelium to the sum of the inner and the outer surface density of the epithelium; in this case the sought for thickness value is underestimated and must consequently be multiplied by a factor Ki.Both correction factors are algebraically defined. Their values are calculated and graphically represented as a function of the thyroid activation index (the ratio between the volume density of the epithelium and the colloid) for the range from 0·1 to 100.The validity of the theoretical interpretation of the discrepancy between the values obtained for the average thickness of the thyroid epithelium by the direct and the corresponding values obtained by the indirect method, is empirically tested. It is shown that by the introduction of appropriate correction factors the difference between the results obtained by each method can be reduced. These improved direct and indirect methods for determining the wall thickness of a hollow sphere seem to lend themselves to being used in the stereological analysis of other biological, perhaps even non‐biological materials of similar structure.