Three-dimensional meshwork structure of glomerular basement membrane revealed by chemical treatment

In order to study the three-dimensional ultrastructure of the glomerular basement membrane (GBM), isolated GBM was treated with elastase, sodium dodecyl sulfate, and 2-mercaptoethanol and examined by transmission electron microscopy using ultrathin sectioning method and stereoscopic view. This treatment revealed clearly three-dimensional meshwork structure of GBM mainly composed of type IV collagen. Numerous regular polygonal small pores were present in the meshwork structure. The average short dimension of the small pores was 4.1 +/- 1.8 nm and the average long dimension was 4.8 +/- 2.2 nm. Our present results further support the molecular sieve theory of the basement membrane.