Differential distribution of basement membrane type IV collagen alpha1(IV), alpha2(IV), alpha5(IV) and alpha6(IV) chains in colorectal epithelial tumors.

In this study, we examined the relationship between the histopathological grade and immunohistochemical localization of six genetically distinct type IV collagen alpha chains, the major component of basement membrane (BM), in normal and neoplastic colorectal tissues. In the normal colorectal mucosa, alpha1/alpha2(IV) and alpha5/alpha6(IV) chains were stained in all epithelial BM. However, alpha3/alpha4(IV) chains were restrictively immunostained in the BM of the apical surface epithelium.