Staining Differences in Cell Nuclei

If the parenchymal cells of the liver of the rat, or certain other cells, are stained with a modified Mallory stain or with iron haematoxylin, the nuclei are stained in two different ways. This effect may be observed after various fixatives. Direct microscopical observation shows that when part of a nucleus is cut away by the microtome-knife, the part of it remaining in the section stains differently from an intact nucleus. The probability of a nucleus being wholly or only partly contained in a section of a particular thickness can be calculated. Counts made in sections of various thicknesses show that the proportion of nuclei stained in the different ways is consistent with the calculated probability. It is suggested that the nuclear membrane in the fixed state presents a relatively low permeability.