Automated estimation of diploid and tetraploid nuclei with an electronic particle counter.

A limiting factor in the biochemical quantitation of DNA and other nuclear constituents has been the inaccuracy of the enumeration of nuclei. The hemocytometer method has been accepted as a primary standard for counting nuclei and permits the use of morphologic detail as a means of control [S, 10, 17, 18, 21, 221. However, predictable errors in the hemocytometer method resulting from the Poisson distribution of particles in a relatively small sample are well known to exist. In routine procedures an error of 6.5-9.9 per cent is expected to occur [14]. The hemocytometer method gives no quantitative information concerning nuclear size distribution. This paper describes and evaluates a method for counting and determining the size distribution of isolated diploid and tetraploid hepatic cell nuclei of the rat by means of an electronic particle counter. RNA and DNA values per nucleus are reported for diploid and tetraploid classes.