IMMUNOHISTOCHEMICAL DISTRIBUTION OF TYPE-VI COLLAGEN IN DEVELOPING HUMAN KIDNEY

The distribution of type VI collagen was investigated immunohistochemi cally in the developing human kidney from 15 to 32 weeks gestational a ge and it was compared with that observed in the normal infantile and adult human kidney. In fetal kidney, type VI collagen was widely distr ibuted as a fibrillar network in the subcapsularly undifferentiated me senchyme and intertubular interstitium, and as a basement membrane-lik e structure around the ureteral bud branches, tubules, and collecting ducts. During nephrogenesis, type VI collagen disappeared from the ind uced mesenchyme close to the tips of ureteral branches, while it forme d a distinct basement membrane-like structure around the early stages of nephron differentiation (comma-shaped and S-shaped bodies) and late r along Bowman's capsule of capillary loop and maturing glomeruli. A s trong immureactivity for type VI collagen was also found in the glomer ular basement membrane and mesangial areas of capillary loop and matur ing glomeruli. In infantile kidney, type VI collagen showed a distribu tion pattern similar to that observed during the fetal period. In adul t human kidney, glomerular basement membrane showed a weak positivity for type VI collagen and the basement membrane-like staining around Bo wman's capsule, tubules, and collecting ducts was less evident than in fetal and infantile kidney. Our immunohistochemical findings suggest that type VI collagen is a normal component of the glomerular and extr aglomerular extracellular matrix of developing human kidney and that i t undergoes changes in the expression during maturation.