Some Stereological Principles in Morphometric Cytology

In this paper several statistical methods are developed that are of use in morphometric cytology, for the purpose of obtaining three-dimensional information from two-dimensional measurements made on cell sections. An estimator is described for counting $N_V $, the number of organelles (e.g., mitochondria) per unit of cellular volume. Unlike those currently employed, this estimator for $N_V $ does not depend on the sizes of the organelle bodies. The remainder of the paper discusses the axis ratios, $t$, of elliptical cross sections that are the intersections of an ellipsoid with random planes. For prolate spheroids, an explicit formula is developed for the probability density. For general ellipsoids, a numerical method is presented for calculating the distribution function. As one approach toward deriving information about organelle shape, frequency distributions of $t$ derived by these techniques may be compared with experimental frequency distributions of the axis ratios of organelle cross sections.