Expression of Transforming Growth Factor-Alpha in the Human Ovary During Follicular Growth, Regression and Atresia

Abstract

The Cytologic Localization and Cellular Levels of Tgfa in the Human Ovary During follicular growth and regression were examined by avidin/biotin immunoperoxidase techniques with a monoclonal antibody to TGFa. In primordial follicles, only the oocyte showed intense immunostaining for TGFa, whereas the flattened pregranulosa cells were negative for the immunostaining. The earliest stage of follicular growth at which immunostaining for TGFa in granulosa cells and theca interna cells became apparent was the preantral stage. With the increase in the size of follicles, the intensity of TGFa immunostaining in the oocyte decreased, whereas the staining intensity of the granulosa and theca cells increased. The immunostaining for TGFa in granulosa and theca interna cells persisted in the corpus luteum, and further intensified during the midluteal phase. In the regressing corpus luteum, the immunostaining was present only in the peripheral theca lutein cells adjacent to the central scar tissue. The corpus albicans was negative for the immunostaining. Stromal cells exhibited weak staining for TGFa. In atretic follicles, the theca interna cells exhibited intense staining for TGFa without appreciable staining in the scattered granulosa cells. This is the first report to demonstrate that TGFa expression in the oocyte is maximal in primordial follicles, whereas TGFa expression in granulosa and theca cells increases with the progress of follicles and reaches its maximum in the lutein cells during the mid luteal phase. These features of developmental stage-dependent expression of TGFa in the human ovary suggest the possible participation of TGFa in the regulation of initial growth of the oocyte in early folliculogenesis and steroidogenic function of growing follicles. Furthermore, the increased expression of TGFa in the theca interna cells of atretic follicles and theca lutein cells peripheral to the regressing corpus luteum implies that TGFa may participate in the transformation of theca cells into stromal cells to remodel the local tissue following atresia and luteolysis in the human ovary. © 1994, The Japan Endocrine Society. All rights reserved.