Immunohistochemical detection of type I, III, and IV collagen in endometriosis implants

OBJECTIVE: To determine if types I, III, or IV collagen are present in ectopic endometrium and to determine which type(s) of collagen are present in the connective tissue surrounding ectopic endometrial implants. DESIGN: Paired intrauterine and ectopic endometrial samples were obtained for study at the time of laparoscopy from women in the proliferative and secretory phase of the menstrual cycle. Connective tissue surrounding each ectopic implant was also obtained for study. SETTING: Academic research environment with institutional review board approval. PATIENTS: Six patients without endometriosis were used as controls. Ten additional patients with stage II or III endometriosis were studied. Only women on no medications participated in the study. MAIN OUTCOME MEASURES: Immunohistochemical techniques were used to identify the presence of collagen in biopsied specimens. RESULTS: Each collagen type studied was identified in the intrauterine endometrium of patients with and without endometriosis. All collagen types were also identified in each of the ectopic endometrial implants studied. The distribution of collagen in ectopic endometrial implants was similar to the distribution of collagen seen in intrauterine endometrium obtained from patients with or without endometriosis. Collagenous tissue that contained type I collagen was identified at the periphery of deep ectopic implants. CONCLUSIONS: This study demonstrates the presence of type I, III, and IV collagen in the intrauterine and ectopic endometrium of patients with endometriosis. Type I collagen was the predominant collagen present in the surrounding collagenous tissue associated with deep, ectopic endometrial implants.