Sex chromatin determination in formalin-fixed, paraffin-embedded tissues of rats.

Distinctive chromatin bodies appearing in interphase nuclei of mammalian female cells have been found in most mammalian species. The positive correlation between sex chromatin masses and mammalian female tissue presents an almost ideal criterion for sex determination of mammalian tissues. Previous studies indicate that this positive correlation exists in fresh and formalin-fixed, paraffin-embedded normal and tumor tissue of humans, as well as in fresh squash preparations of normal and tumor tissues of rodents. In this experiment we have shown that it is also possible to determine sex in formalin-fixed, paraffin-embedded normal and tumor tissue of the rat.