The use of polyethyleneimine for demonstration of anionic sites in basement membranes and collagen fibrils.

strated that after an intravenous injection of cationic polyethyleneimine (PEI) into rats, this molecule could be found in the glomeruli at the epithelial and endothelial sides of the glomerular basement membrane. PEI was suggested as a tracer particle for anionic sites in electron microscopy. We now report on the localization of PEI in lung, choroid plexus, blood vessels and collagen. Four-month-old female wistar rats of about 200 g were injected in the tail vein with 0.2 nil 0.5% PEI (m.w. 30,000-40,000) solution adjusted to pH 7.3 with HCI. The osmolarity was brought to 400 mOsm with NaCI. Fifteen minutes after injection, small tissue blocks were taken and immersed in 2% phosphotungstic acid (PTA) and 0.1% glutaraldehyde (GA) mixture