Quantitative analysis of type IV collagen alpha chains in the basement membrane of human urogenital epithelium.

Type IV collagen is a major component of the basement membrane (BM), which consists of six genetically distinct alpha(IV) chains. In this study the expression of these six alpha(IV) chains was demonstrated immunohistochemically. In addition, the alpha2(IV) and alpha5(IV) chains were analysed quantitatively by confocal laser scanning microscopy in human urogenital epithelial BM. The alpha1/alpha2(IV) and alpha5/alpha6(IV) chains were immunoreactive in the epithelial BM, whereas, alpha3/alpha4(IV) chains were not. The quantitative analysis revealed that the amount of alpha2(IV) and alpha5(IV) chains differed in each urogenital epithelial BM. The content of alpha5(IV) chains in the epithelial BM of the bladder was differentially high, and that of the foreskin was differentially low. It is concluded that the elasticity of epithelial BM of the bladder may be structurally related to the high content of alpha5/alpha6(IV) chains.