Image analysis of hepatocyte nuclei in assessing di(2-ethylhexyl)phthalate effects eluding detection by conventional...

The effect of di(2-ethylhexyl)phthalate (DEHP) administered in single intraperitoneal doses of 30, 300 and 3000 mg/kg in Syrian golden hamsters was studied by means of routine pathologic investigations, electron microscopy and image analysis. The morphological evaluations did not show apparent differences between the control and treated animals. Such differences, however, were recognized by using image analysis. They concerned morphology of the hepatocyte nuclei and were defined by quantitative parameters reflecting geometrical, optical and structural properties. Of importance for differentiating dose/effect relationships were features of chromatin structure. In order to describe those features we developed special algorithms capable of identifying and characterizing regions of condensed chromatin as subimages. These were distinguished by their size, shape and optical density and showed typical distributions within the nucleus. As our results demonstrate, image analysis methods permit detection of DEHP related pathology in animals which, as far as is evident from routine morphologic evaluations, belong to the no-effect experimental group.