A comparison of several methods for stereological determination of the numbers of organelles per unit volume of cytoplasm

SUMMARY Granules in electron micrographs of normal rat peritoneal macrophages were analysed using a number of stereological procedures currently available for estimating the numbers of discrete particles from measurements made on random sections. The distinction between the various procedures was dependent upon the nature of the parameters derived from micrograph samples, and upon the degree to which particle shape and size distribution coefficients were incorporated within the mathematical derivations. Whilst all methods were found to produce similar estimates of granule number per unit volume of macrophage cytoplasm, two procedures demonstrated a greater degree of flexibility of application. It is concluded that these two methods may possess important advantages when quantitating experimental systems exhibiting alterations in particle morphology.