Ultrastructural tubular basement membrane lesions in adult polycystic kidney disease.

The pathogenesis of adult polycystic kidney disease (PCKD) remains an enigma. In an attempt to find a defect that might explain the cyst formation, an ultrastructural study was performed on seven fresh bilateral nephrectomies of seven patients suffering from adult PCKD. Marked electron microscopic changes of the tubular basement membranes were detected, including thickening, splitting, fraying, and multilayering of the basement membranes. By contrast, glomerular basement membranes lacked these alterations. The kidneys from two control groups (five donor kidneys harvested for transplantation; 10 patients who suffered from end stage renal disease) showed none of the lesions detected in the polycystic kidneys. The lesions of the tubular basement membrane, the principal support of tubular wall, may be the primary phenotypic expression and cause of the inherited defect.