Expression of transforming growth factor-alpha in the human ovary during follicular growth, regression and atresia

The cytologic localization and cellular levels of TGF alpha in the human ovary during follicular growth and regression were examined by avidin/biotin immunoperoxidase techniques with a monoclonal antibody to TGF alpha. In primordial follicles, only the oocyte showed intense immunostaining for TGF alpha, whereas the flattened pregranulosa cells were negative for the immunostaining. The earliest stage of follicular growth at which immunostaining for TGF alpha in granulosa cells and theca interna cells became apparent was the preantral stage. With the increase in the size of follicles, the intensity of TGF alpha immunostaining in the oocyte decreased, whereas the staining intensity of the granulosa and theca cells increased. The immunostaining for TGF alpha 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 TGF alpha. In atretic follicles, the theca interna cells exhibited intense staining for TGF alpha without appreciable staining in the scattered granulosa cells. This is the first report to demonstrate that TGF alpha expression in the oocyte is maximal in primordial follicles, whereas TGF alpha 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.(ABSTRACT TRUNCATED AT 250 WORDS)