Glomerular basement membrane necrosis and crescent organization

Abstract

In order to reveal structural damage to the glomerular basement membranes occurring in crescentic glomerulonephritis and the subsequent connective tissue organization of the crescent, 14 kidney biopsies were treated with detergents to remove cellular components and the tissue remaining examined by transmission (TEM) and scanning (SEM) electron microscopy. The fourteen biopsies were divided into two groups for analysis. Group I (7 cases) contained necrotizing lesions and cellular crescents. Acellular TEM (ATEM) revealed widespread lysis of mesangial matrix, while acellular SEM (ASEM) of five cases revealed three general patterns of GBM necrosis. Group II (7 cases) contained fibrocellular and fibrosis crescents. ATEM and ASEM revealed that collagen fibers initially form along fibrin fibrils and eventually result in formation of lacunar spaces occupied by cells of the crescent. Fibrous crescents were associated with prominent glomerular tuft distortion and entrapment of normal capillary loops. Continuity between interstitial space, matrix of crescent and mesangium were often observed. These observations suggest that lysis of mesangial matrix is extensive and precedes GBM lysis while the pattern of GBM damage fits best with local release of lytic factors. Furthermore, the architectural distortion and continuity which develops between normally segregated compartments (mesangial-interstitial) indicate that both the initial necrosis and the reparative response to injury, contribute substantially to overall nephron dysfunction.