Increase in the number of fenestrae in mouse endothelial liver cells by altering the cytoskeleton with cytochalasin B

Endothelial cells of the hepatic sinusoid isolated from mice livers and maintained in culture display typical fenestrae grouped in sieve plates. Treatment with cytochalasin B led to no significant change in the mean diameter of the fenestrae but to an increase in their number and in the porosity of the cells (percentage of the cellular surface opened by the fenestrae) which attained up to 300% of that of the controls. Scanning electron microscopic observations of Triton-extracted cells revealed that these modifications were related to an alteration of the cytoskeleton. The effect of cytochalasin B could be reversed; 3 hr after removal of the drug, the cells recovered their original aspect with sieve plates scattered over their surface. These observations demonstrate that endothelial fenestrae are inducible structures and that the cytoskeleton seems to be involved in their formation.