Rat ciliary process in chronic serum sickness: light, immunofluorescence, and electron microscopy.

The ciliary processes of 26 male Wistar rats that survived a prolonged period of immunization with bovine serum albumin (BSA) and a similar number of age- and sex-matched controls were studied by immunofluorescence and electron microscopy. The findings in the ciliary process were compared with those of the renal glomeruli. Granular subepithelial deposits of rat IgG, C3, and BSA were demonstrated by direct immunofluorescence in the ciliary process and renal glomeruli of 38% and 85% of experimental animals, respectively. Electron microscopy of the positive immunofluorescent cases disclosed electron-dense single masses and clusters in the basement membrane regions below the epithelial layers. Experimental chronic serum sickness appears to offer an excellent approach toward understanding the pathogenesis of uveal involvement in human serum sickness and in the "collagen-vascular" diseases.