Morphometric measurement of cellular hypertrophy.

This study is a comparison of two morphometric methods for measuring mean cellular hypertrophy. One method, based on the relatively simple point-counting technique used to determine nuclear to cytoplasmic ratios, measures increases in mean cell volume per nuclear volume. The second method, involving nuclear profile counting in tissue sections of different known thicknesses, evaluates the increase in mean cell volume per nucleus. The latter method is considered more accurate because of the significantly greater amount of tissue sampling utilized. Furthermore, cellular hypertrophy is better defined by the increase in cell size per nucleus than by a change in the cell to nucleus volume ratio, values that can be numerically equal only if mean nuclear volume remains constant. Thus, comparison of these methods is a way to evaluate either the reliability of the point-counting technique or the equivalent hypothesis that mean nuclear volumes do not vary significantly during periods of growth. Cellular hypertrophy has been measured in 18 examples of normal tissue growth and 18 examples of induced growth. Five cell types are included: cardiac myocytes, aortic smooth muscle cells, capillary endothelium, and glomerular mesangial and epithelial cells. Little agreement was found between the two methods of measurement. Mean nuclear hypertrophy varied widely and unpredictably, more than +/- 20% in the majority of cell populations. It is concluded that the point-counting method alone is unreliable as a quantitative measure of cellular hypertrophy.