An interferometric analysis of nucleoli in cultured mesothelial cells

Previous studies have indicated that total nucleolar area and volume remain constant regardless of the number of nucleoli. The question remains whether this relationship is valid for mass. To answer this, total nucleolar mass values were obtained from nuclei of living mesothelial cells in culture possessing one to four nucleoli. The nucleolar mass was calculated using interferometry. The mean total nucleolar dry mass for cells with one, two, three, and four nucleoli was 40 × 10⁻¹²gm, 38.4 × 10⁻¹²gm, 39.1 × 10⁻¹²gm, and 41.4 × 10⁻¹²gm, respectively. These data suggest that on the average, each cell had approximately the same total nucleolar dry mass regardless of the number of nucleoli. In an additional study, interferometry was employed to reveal changes in nucleolar mass and concentration during a seven‐hour period. It was concluded that the nucleolus is a dynamic organelle, with its total mass varying in time from an average 40 × 10⁻¹²gm with a mean concentration of 22.2gm/100cm³.