PRESENCE OF TRANSFORMING GROWTH FACTOR-ALPHA MESSENGER-RIBONUCLEIC-ACID (MESSENGER-RNA) AND ABSENCE OF EPIDERMAL GROWTH-FACTOR MESSENGER-RNA IN RAT OVARIAN GRANULOSA-CELLS, AND THE EFFECTS OF THESE FACTORS ON STEROIDOGENESIS INVITRO

Granulosa cell steroidogenesis has been reported to be modulated by transforming growth factor-alpha (TGFalpha) and its biochemical and physiological analog, epidermal growth factor (EGF). In this report, we studied whether TGFalpha or EGF mRNA is produced by granulosa cells, examined the morphological effects of TGFalpha or EGF on granulosa cell cultures, and measured the changes in granulosa cell progesterone production in cells cultured with TGFalpha or EGF. RNA from fresh granulosa cells and from those incubated overnight and for 4, 7, and 10 days with FSH was studied with reverse transcription-polymerase chain reaction for TGFalpha and for EGF. Only TGFalpha mRNA appeared to be present in the granulosa cells. Phase-contrast microscopy revealed that the combination of FSH plus TGFalpha or EGF resulted in cell shape changes and an increase in lipid droplets in the granulosa cells. Electron microscopy revealed that the endoplasmic reticulum increased in the granulosa cells incubated with either EGF or FSH plus EGF. Mitochondria of granulosa cells incubated with growth factors possessed ultrastructural features consistent with those found in preovulatory granulosa cells. Culture of the granulosa cells with FSH plus TGFalpha or with FSH plus EGF resulted in significantly elevated progesterone and 20alpha-hydroxyprogesterone levels. The highest level of progesterone production was on the eighth day of culture. We conclude that TGFalpha mRNA is produced by granulosa cells and that granulosa cell differentiation, as defined by morphological and biochemical criteria, is significantly stimulated in vitro by the combination of FSH and TGFalpha.