Gaps of the glomerular capillary basement membrane were observed by electron microscope in 8 of 44 biopsies from the patients with a variety of renal diseases. Ultrastructural changes of gaps were classified into 4 types according to Stejskl’s classification. Type I

segmental lamination and destruction of the basement membrane with necrosis of the podocytes and endothelial cells; Type II

segmental lamination and lysis of the basement membrane without cellular necrosis; Type I

gaps of the capillary basement membrane filled with extensive intramembranous deposits; Type VI

gaps of the capillary wall are partially or completely sclerotic glomeruli

several gaps being seen in the wall of a single capillary.It is generally thought that the presence of gaps in the glomerular capillary basement membrane is a morphologic indication of proteinuria and hematuria