Alterations in Endothelial Fenestrations in Liver Sinusoids of Baboons Fed Alcohol: A Scanning Electron Microscopic Study

The effects of chronic alcohol consumption on the ultrastructure of endothelial fenestrations in liver sinusoids were studied by scanning electron microscopy in surgical liver biopsies of 16 baboons pair‐fed with nutritionally adequate diets containing alcohol or isocaloric carbohydrate for up to 112 months. Alcohol consumption for 4 to 24 months resulted in a decreased number of fenestrations (1.4 per μm² of the endothelial surface vs. 3.3 in pair‐fed controls; p < 0.01) and an increase in their geometric mean diameter (115.6 vs. 82.3 nm in controls; p < 0.001). After 61 to 112 months of alcohol feeding, the number of fenestrations was 1.9 (vs. 4.6 in controls; p < 0.005) and the fenestration diameter was 91.8 nm (vs. 76.7 nm in controls; p < 0.01). The fractional areas occupied by the fenestrations on the endothelial surface of the sinusoids in baboons fed alcohol for 4 to 24 and 61 to 112 months were calculated to be 84 and 58% of their respective controls. The alterations in the sinusoidal endothelium revealed in this study are most likely associated with a disturbance in the exchanges between the sinusoidal blood stream and the liver parenchyma and may thereby contribute to alcohol‐induced liver injury.