Background Despite advancing female age becomes an important factor for increasing incidence of infertility, it remains a difficult problem in infertility treatment. A major cause for age related decline of fertility is the deterioration of oocyte quality and ovarian response. However, there is no clinically effective method to improve the oocyte quality in old women. Ovarian angiogenesis plays an important role in follicular growth and the selection of dominant follicle by allowing the delivery of adequate nutrition, hormonal supply and oxygen from stromal blood vessels to induce oocytes with high quality. Tatone et al. suggested a possible mechanism that age related nuclear and cytoplasmic damage may occur as a result of inadequate ovarian angiogenesis in primordial follicles as well as in ovarian stroma vessels.

These results suggest that the activation of ovarian angiogenesis could be a new strategy for the improvement of age related decline of oocyte quality. Bone morphogenetic proteins are members of the transforming growth factor B superfamily which plays a critical role in the development of mammalian ovarian follicles. Mutations in the Bmp genes or their Inhibitors,Modulators,Libraries receptors result in impaired female fertility such as decreased granulosa cell proliferation, abnormal oocyte growth, and failure of follicle development. The BMP 6 is highly expressed in mammalian oocytes as well as other cell types. In vitro extensive studies have showed that BMP 6 seems to affect gonadotropin signals in granulosa cells of several mam malian species, although it offered conflicting results.

In vivo study using BMP 6 null mice also demonstrated that BMP 6 promotes normal fertility by enabling appropriate response to LH and normal oocyte quality. Besides this role, BMP 6 has a potential role in regulation of angiogenesis by affecting endothelial cells differentiation, migration, proliferation, and tube formation. BMP 6 regulates the Inhibitors,Modulators,Libraries expression of inhibitor of DNA binding proteins in the ovine ovarian follicles. Id proteins are negative transcriptional regulators, which lack a basic Inhibitors,Modulators,Libraries DNA binding domain and block subsequent transcriptional activity by forming heterodimer with helix loop helix transcription factor. It has been speculated that Ids are involved in the control and timing of follicle selection and Inhibitors,Modulators,Libraries granulosa cells differentiation in avian species. Mammalian Id superfamily consists of four isoforms. Especially, Id 1 is a well characterized target Inhibitors,Modulators,Libraries of BMP 6 signaling and plays a role in angiogenesis through activation of the vascular endothelial growth factor. However, to our knowledge, there have been no studies selleck bio on the effects of BMP 6 on ovarian response and angiogenesis, and oocyte quality according to the female age.