Immunohistochemical studies on collagen types in the uterine cervix in pregnant and nonpregnant states

Abstract The distribution of collagen types in pregnant and nonpregnant uterine cervices was examined by immunoperoxidase staining with the use of type-specific anticollagen antibodies. The nonpregnant cervix, composed of dense fibrous tissues, was diffusely stained with antibodies to type I and type III collagens. Type IV collagen was located only in the basement membrane region. In the cervix at term pregnancy, a marked decrease in fibrous connective tissue with increased proportions of smooth muscle fibers was characteristic, forming expanded spaces in between due to edema (clear spaces) with focal infiltrations of polymorphonuclear leukocytes. Type I and type III collagens were distributed only around smooth muscle fiber bundles with some fibroblasts attached. Type IV collagen was distributed in a linear fashion delineating individual smooth muscle fibers and vascular basement membranes. A possible role of infiltrated polymorphonuclear leukocytes in the dissociation of fibrous connective tissues of the cervix at term pregnancy is discussed.