Changes in mouse hepatocytes caused by vincamin. A thin-sectioning and freeze-fracture study

Mouse liver was examined following a single intraperitoneal application of 25 mg/kg body weight vincamine. The studies were made using the technique of thin-sectioning for electron microscopy as well as the freeze-fracture method. The thin-sectioning technique was useful for observing discrete changes such as an increase in the mitochondria and alterations in the bile canaliculi, e.g. a loss of microvilli and dilatation of the lumen. No other cytoplasmic changes could be observed. It was only with the aid of the freeze-fracture method that alterations in the cell contacts became visible. In contrast to the control animals the tight junctions in the liver tissue of mice treated with vincamin were disorganized and irregularly arranged. The gap junctions showed a very irregular contour as well. The question arises as to the extent to which the freeze-fracture method should be applied in the testing of pharmaceuticals, so as to exclude the possibility of damage to membranes.