Immunohistochemical analysis of collagen expression in uterine leiomyomata during the menstrual cycle.

To investigate the possible involvement of collagen in the characteristic features of human leiomyoma, type I, III and IV collagen expression was determined at the protein level in normal myometrium and leiomyoma tissues throughout the menstrual cycle. The tissues were obtained from 40 pre-menopausal women (29-53 years of age) at various stages of the menstrual cycle who were undergoing abdominal hysterectomy for symptomatic uterine leiomyoma. Immunohistochemical staining was performed with specific monoclonal antibodies against type I, III and IV collagen in the leiomyoma and the myometrial tissues. Immunohistochemical analysis revealed that type I collagen expression was increased in the leiomyoma tissues at the protein level as compared to that in the normal myometrium tissues throughout the menstrual cycle. These results suggest that increased expression of type I collagen plays a key role in the pathogenesis of uterine leiomyoma.