A NOVEL STRUCTURE INVOLVED IN THE FORMATION OF LIVER ENDOTHELIAL-CELLFENESTRAE REVEALED BY USING THE ACTIN INHIBITOR MISAKINOLIDE

Hepatic endothelial fenestrae are dynamic structures that act as a sie ving barrier to control the extensive exchange of material between the blood and the liver parenchyma. Alterations in the number or diameter of fenestrae by drugs, hormones, toxins, and diseases can produce ser ious perturbations in liver function. Previous studies have shown that disassembly of actin by cytochalasin B or latrunculin A caused a rema rkable increase in the number of fenestrae and established the importa nce of the actin cytoskeleton in the numerical dynamics of fenestrae. So far, however, no mechanism or structure has been described to expla in the increase in the number of fenestrae, Using the new actin inhibi tor misakinolide, we observed a new structure that appears to serve as a fenestrae-forming center in hepatic endothelial cells.