Expression of transforming growth factor-alpha and myc oncoprotein in the human ovary during follicular growth, atresia and corpus luteum formation regression

Objective: To investigate the expression of transforming growth factor (TGF)-alpha and myc oncoprotein on human follicular development and atresia in vitro.

Methods: Ovarian tissues were obtained from 36 women with regular menstrual cycles who underwent abdominal hysterectomy for a variety of gynecological conditions. Expression of TGF-alpha and myc protein in the ovarian tissues was examined by immunohistochemical technique.

Results: In primordial follicale only the oocyte showed intense immunostaining for both TGF-alpha and myc oncoprotein. Immunostaining for TGF-alpha in granulosa cells and theca interna cells became apparent in the follicles of preantral stage. With the increase in the size of follicles the intensity of immunostaining in the oocyte decreased, whereas the staining intensity of the granulosa and theca cells increased, and persisted in the corpus luteum and further intensifying during the midluteal phase. myc protein expression in granulosa cells was apparent only in the preantral follicle stage. In the regressing corpus luteum, expression of both TGF-alpha and myc oncoprotein was restricted only in the peripheral theca lutein cells adjacent to the central core of scar issue. In atretic follicles theca interna cells exhibited prominent immunostaining for TGF-alpha and myc protein.

Conclusions: TGF-alpha and myc oncoprotein combination play a role as intraovarian regulators through autocrine and paracrine mechanism and may participate in remodelling the initial growth of the oocyte, follicular growth, differentiate and apoptosis.