Scheme of filtration barrier (blood-urine) in the kidney. A. The endothelial cells of the glomerulus; 1. pore (fenestra). B. Glomerular basement membrane: 1. lamina rara externa 2. lamina densa 3. lamina rara interna C. Podocytes: 1. enzymatic and structural protein 2. filtration slit 3. diaphragma