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The distribution of the collagen chains from αα1(IV) to αα6(IV) could serve as a basis for the characterization of type IV collagen. In this study, immunohistochemistry of the ocular anterior segment of adult mice was performed using specific monoclonal antibodies against each chain in the series from αα1(IV) to αα6(IV). The results show that the components of type IV collagen in vascular basement membranes are αα1(IV) and αα2(IV) with or without αα5(IV) and αα6(IV) chains and those in epithelium and muscle basement membranes are αα1(IV), αα2(IV), αα5(IV), and αα6(IV) chains. In corneal endothelium, pigmented epithelium of iris and ciliary body, and trabecular meshwork, αα3(IV) and αα4(IV) chains are also expressed in addition to αα1(IV), αα2(IV), αα5(IV), and αα6(IV) chains. Moreover, we investigated the change in molecular composition in ciliary body during postnatal development. αα3(IV) and αα4(IV) chains were also expressed in addition to αα1(IV), αα2(IV), αα5(IV), and αα6(IV) chains in ciliary pigmented epithelium basement membrane from 7 days after birth. This result suggests that the basement membranes gradually change their biochemical features owing to temporal regulation. Taken together, these findings suggest that the different distribution and the developmental expression of αα1(IV) to αα6(IV) chains are associated with the tissue-specific function of type IV collagen in basement membranes. [ABSTRACT FROM AUTHOR]