Proteins on the luminal surface of the mammalian membrane urothelium form an hexagonal two-dimensional (2D) lattice of approximately 12 nm particles embedded in a lipid matrix. The establishment and/or maintenance of this two-dimensional lattice have not yet been elucidated. To understand the lipid involvement in these effects, which may have a potential role on the permeability barrier, the lattice structural changes induced by different dietary fatty acids were analyzed. Image analysis of the uranyl formate stained urothelial membrane from mice fed with a commercial diet (control) or a formula containing 5% (w/w) corn oil (CO) or olein (O) and our previous data of fluorescence anisotropy indicated that the olein diet profoundly alters the two-dimensional particle network. Besides the increase from 15 nm (control) to 17 nm center-to-center particle, a statistically significant increase of the particle size was induced by the olein diet. The same parameters on urothelial membranes from animals fed with a corn diet differed on the long-range super-array from the control values. A specific structural change of the urothelial plaque particle organization as a response to changes of lipid composition is described for the first time. These results are a starting point for further research of the lipid implications on the permeability barrier. (c) 2005 Elsevier Inc. All rights reserved.