SCANNING AND TRANSMISSION ELECTRON-MICROSCOPIC STUDIES OF NORMAL AND DIABETIC ACELLULAR GLOMERULAR AND RETINAL MICROVESSEL BASEMENT-MEMBRANES

Basement membranes (BMs) were first described in the mid-19th century, but they were not isolated and prepared for compositional studies unt il nearly 100 years later. Early methods of isolation were carried out on renal glomeruli, which were first sub-fractionated from kidney tis sues by sieving. BMs were then isolated from the glomeruli by ultrason ic disruption, which, following low speed centrifugation, yielded ''pu rified'' but highly fragmented BM material. In an effort to obviate th e mechanical damage to BMs produced by ultrasound, a sequential deterg ent solubilization technique was introduced that resulted in morpholog ically intact BMs from a variety of tissue sub-fractions. This was hig hly advantageous because ''acellular'' BMs produced by the procedure c ould be examined critically by light and electron microscopic methods. Subsequently, this procedure has been utilized to demonstrate the sub structural heterogeneity of vascular and non-vascular BMs from a wide variety of animal species. The current review describes the results of scanning and transmission electron microscopic studies of acellular B Ms prepared from renal glomeruli and from the retinal microvessels of the eye. These BMs are of particular interest to basic scientists and clinicians because they are altered in several disease states, most no tably diabetes mellitus, An effort is made to point out the implicatio ns of glomerular and retinal vessel BM changes to the pathogenesis of diabetic kidney and retinal vessel BM disease. (C) 1994 Wiley-Liss, In c.