Local extra- and intra-ovarian factors: control of in-vitro growth and differentiation in mice follicles Running title: Ovarian factors and follicle differentiation

Regulation of ovarian activity is an integrated process encompassing both extraovarian signals and intra-ovarian factors. Ovarian functions result from the evolution of a morphological unit, the ovarian follicle, which consists of a central oocyte surrounded by granulosa cells and other layers of somatic theca cells. The maturation of the follicle proceeds through primordial, primary, and secondary stages of development and is controlled by various factors produced in the ovary. Locally produced growth factors, the members of the transforming growth factor-β super-family, work in concert with gonadotropins throughout the follicular growth and have significant effects on follicle selection. The complexity of the interrelation of the events controlling follicular growth and ultimate acquisition of developmental competence is under continuous investigation. It is generally believed that follicular atresia and luteolysis occur by mechanisms that accompany a highly organized type of cell death, called programmed cell death or apoptosis. The present review reports a variety of intra-ovarian factors, involved in the follicular development. Elucidation of the mechanisms that regulate follicular development may lead to the prevention of female reproductive disorders or other pathological conditions and to the development of new culture methods for in-vitro maturation (IVM) and in-vitro fertilization (IVF) of the mice follicles.

Keywords:

Mice , follicle , intra-ovarian factors , growth factors , in-vitro maturation