Polychlorinated biphenyl congener 153-induced ultrastructural alterations in rat liver: a quantitative study

Alterations in the liver of male and female Sprague-Dawley rats fed PCB congener 153 (2,2',4,4',5,5'-hexachlorobiphenyl) at 0.5, 5, or 50 ppm concentrations in diets for 13 weeks were determined morphometrically. A dose-dependent increase in hepatocyte volume was detected; the cytoplasmic compartment contributed to the increase in cell volume in an overwhelming fashion. Eighty percent and 250% increase in smooth endoplasmic reticulum volume and its surface area in hepatocytes were estimated in animals of both genders from 5- and 50-ppm groups, respectively; the organelle played the largest part in the increase in cytoplasmic volume. Rough endoplasmic reticulum alteration was shown to depend on gender, where the volume per hepatocyte was augmented by 40% and 45% in females of 5- and 50-ppm groups, respectively, however, 30% and 20% decreases in volume of this organelle were noted in males at those congener concentrations. A decrease of 13% in normal mitochondria volume at 50 ppm concentration was observed, which may have been a consequence of a transformation of these mitochondria to abnormal types. Two types of abnormal mitochondria, named Type I and Type II, were defined: the former comprised mitochondria that had cristae which laying parallel to the long axis of the organelle and the latter showed C- or ring-shaped profiles. Data analysis revealed a trend toward an increase in abnormal mitochondria volume in the cells as the congener concentration elevated. In addition, a threefold increase in the volume of lysosomal elements per hepatocyte was noted in 50 ppm PCB-fed rats of both genders. Also, a significant increase in peroxisome volume per cell in female rats was detected at a lower concentration than it was in the male. This study, which is a first ultrastructural quantitative investigation on the effects of a PCB that included many parameters. The methodology, and the data may prove useful to provide better understanding of pathology in the evaluation and regulation of toxic chemicals.