Estimation of the mean caliper diameter of cell nuclei. II. Various cell types in rat lung

Morphometric studies of lung tissue in which the number of cell nuclei (therefore cells) are determined require the determination of the mean caliper diameter for each type of cell nucleus studied. We determined the mean caliper diameter for the five most common classes of cells found in the gas exchange portion of rat lung. This was done by serially sectioning through ten nuclei from each class of cells and then constructing wax models of the nuclei. Most of the nuclei were found to be triaxial ellipsoids and direct measurements taken from the models were used to calculate the following estimated overall mean caliper diameters (+/-SE): alveolar type I nuclei, 7.97+/-0.2 micrometers, alveolar type II nuceli, 6.77 +/-0.19 micrometers, interstitial cell nuclei, 7.64+/-0.35 micrometers, endothelial cell nuclei, 7.22+/-0.19 micrometers, and alveolar macrophage nuclei, 7.65+/-0.17 micrometers.