{"paper_id":"d012585f-89d2-4516-b8e8-7398bfe37131","body_text":"Summary\nTo determine whether myometrial smooth muscle is newly produced at the endometrio-myometrial junction (EMJ) of the adult uterus, we examined the ultrastructure of mesenchymal components at this site during the menstrual cycle and during early pregnancy. Cells having some features of smooth muscle were found among the usual endometrial stromal cells in every specimen examined. In the follicular phase of the menstrual cycle, such cells resembled myofibroblasts, but in the luteal phase and during early pregnancy, they had more distinct cytoplasmic filaments with dense bodies and dense plaques, and other fairly well developed characteristics of smooth muscle. The identification of smooth muscle-like cells at the EMJ in the adult uterus and the finding that their morphology changes into cells having many of the characteristics of smooth muscle cells during the luteal phase and early pregnancy, suggests that smooth muscle differentiation possibly occurs from multi-potential mesenchymal cells in the endometrial stroma.\nSimilar content being viewed by others\nReferences\nBird CC, Willis RA (1965) The production of smooth muscle by the endometrial stroma of the adult uterus. J Pathol Bacteriol 90:75–81\nBo Wj, Odor DL, Rothrock ML (1968) Ultrastructure of uterine smooth muscle following progesterone or progesterone-estrogen treatment. Anat Rec 163:121–132\nBurnstock G (1981) Development of smooth muscle and its innervation. In: Bulbring E, Brading SF, Jones AW, Tomita T (eds) Smooth Muscle. Edward Arnold, London, pp 431–457\nCozzutto C (1981) Uterus-like mass replacing ovary. Arch Pathol Lab Med 105:508–511\nFujii S, Okamura H, Nakasima N, Ban C, Aso T, Nishimura T (1980) Leiomyomatosis peritonealis disseminata. Obstet Gynecol 55:79s-83s\nFujii S, Nakashima N, Okamura H, Takenaka A, Kanzaki H, Okuda Y, Morimoto K, Nishimura T (1981) Progesterone-induced smooth muscle-like cells in the subperitoneal nodules produced by estrogen. Am J Obstet Gynecol 139:164–172\nGabbiani G, Ryan GB, Majno G (1971) Presence of modified fibroblasts in granulation tissue and their possible role in wound contracture. Experimentia 27:549\nGhahdially FN (1982) Ultrastructural Pathology of the Cell and Matrix. 2nd ed, Butterworth, London, pp 658–663\nKawaguchi K, Fujii S, Konishi I, Okamura H, Mori T (1985) Ultrastructural Study of cultured smooth muscle cells from uterine leiomyoma and myometrium under the influence of sex steroids. Gynecol Oncol 21:32–41\nKonishi I, Fujii S, Ban C, Okuda Y, Okamura H, Tojo S (1983) Ultrastructural study of minute uterine leiomyomas. Int J Gynecol Pathol 2:113–120\nKonishi I, Fujii S, Okamura H, Mori T (1984) Development of smooth muscle in the human fetal uterus: an ultrastructural study. J Anat 139:239–252\nMazur MT, Kraus FT (1984) Histogenesis of morphologic variations in tumors of the uterine wall. Am J Surg Pathol 4:59–74\nParmley TH, Woodruff JD, Winn K, Johnson JWC, Douglas PH (1975) Histogenesis of leiomyomatosis peritonealis disseminata (disseminated fibrosing deciduosis). Obstet Gynecol 46:511–516\nRoss R, Klebanoff SJ (1967) Fine structural changes in uterine smooth muscle and fibroblasts in response to estrogens. J Cell Biol 32:155–169\nScully RE (1981) Smooth-muscle differentiation in genital tract disorders. Arch Path Lab Med 105:505–507\nSkalli O, Ropraz P, Trzeciak A, Benzonana G, Gillessen D, Gabbiani G (1986) A monoclonal antibody against alphasmooth muscle actin: A new probe for smooth muscle differentiation. J Cell Biol 103:2787–2796\nSong J, Mark MS, Lawler MP Jr (1970) Endometrial changes in women receiving oral contraceptives. Am J Obstet Gynecol 107:717–728\nTavassoli FA, Norris HJ (1982) Peritoneal leiomyomatosis (leiomyomatosis peritonealis disseminata): a clinicopathological study of 20 cases with ultrastructural observations. Int J Gynecol Pathol 1:59–74\nAuthor information\nAuthors and Affiliations\nRights and permissions\nAbout this article\nCite this article\nFujii, S., Konishi, I. & Mori, T. Smooth muscle differentiation at endometrio-myometrial junction. Vichows Archiv A Pathol Anat 414, 105–112 (1989). https://doi.org/10.1007/BF00718589\nReceived:\nRevised:\nIssue date:\nDOI: https://doi.org/10.1007/BF00718589","source_license":"CC0","license_restricted":false}