Reevaluation of anionic sites in the rat glomerular basement membrane

We reevaluated the distribution of anionic sites in the glomerular basement membrane with ruthenium red, alcian blue, cationic ferritin, polyethyleneimine, and cationic colloidal gold. Without the accentuation by the metal staining with uranyl acetate and lead citrate, we observed the existence of anionic sites throughout all the layers of the glomerular basement membrane with a similar reticular pattern and the structural difference between the lamina rara and lamina densa, indicating that the lamina rara is an actual structural element.