Immunohistological Study of the Localization of Collagen Types I-XI in Bovine Term Placenta

Abstract

In order to determine the localization of extracellular matrix components in bovine term placenta, the tissue distributions of collagen types I to XI in the amnion, smooth chorion, villous chorion and villi were examined by indirect immunofluorescence microscopy. Collagen types I, III, V, and VI were found in the stroma of the smooth chorion, villous chorion and villi and in the compact layer of the amnion. Type II collagen, which was thought to be present only in cartilage, was found to be distributed in the epithelium of the amnion, stroma of the chorion and trophoblast of the villous chorion. Basement membrane components, type IV and VII collagens, were found to be located not only in the basement membrane but also in the epithelium and compact layer of the amnion. Additionally, type VI collagen was found to be located in the stroma of smooth chorion, and type VII collagen was found to be distributed in the trophoblast layer of the villous chorion. Types VIII, IX, X and XI collagens were found, for the first time, to be distributed in the trophoblast layer, amnion and chorionic epithelium as well as in the blood vessel walls of the chorion. Our results indicated that the compact layer of the amnion contained various types of collagen (I-IX) with various arrangements. However, the fibroblast layer of the amnion contained collagen types III, V and VI but type I collagen could not be observed. The blood vessel wall of the chorion contained all of the types of collagen examined in this study.