Scanning electron microscopy of human urine and purified Tamm-Horsfall's glycoprotein.

Dialyzed and dehydrated human urine and purified Tamm-Horsfall's glycoprotein revealed similar morphology by scanning electron microscopy. Single filaments, with diameters between 15-45 nm, splitting off and merging with thicker fibers at irregular intervals made up a three-dimensional meshwork with submicrometer pores. The resulting "fishing net" is capable of trapping microorganisms and may facilitate their elimination from the urinary tract by micturition. Tamm-Horsfall's glycoprotein may accordingly be a factor protecting against urinary tract infections.