Simple elementary method for the quantification of focal liver lesions induced by carcinogens.

Quantification of focally arranged preneoplastic cell populations in the liver is relevant for numerous experiments. An easy-to-process elementary method is presented for the estimation of the number of foci per cm3 and the size distribution of the foci on the basis of classifying areas of the profiles on the histological section. Using geometrically decreasing size classes, we have obtained the formula: (Formula: see text) where Nn is the number of foci per unit of volume of the size class Kn, Fn is the number of profiles of the class Kn per surface unit and An and Bn are constants dependent on the selection of the boundaries of the size classes. The method presented provides results that are at least as accurate as the values for the numbers of foci per cm3 arrived at by other methods used so far, whereas the distribution of the focus volumes describes the real situation better. It is relatively easy to process the data collected from the section and this can also be done without specific programs developed for this purpose. The method is especially recommended for investigators who only occasionally deal with morphometric questions and are therefore not interested in more complicated methods.