In vitro activation of primordial follicle in sheep ovarian cortex and its development in a three-dimensional co-culture system using theca progenitor cells

IntroductionIn vitro activation and development of primordial follicles from ovarian tissue layer is very important for fertility preservation. The main objective of this study is in vitro activation of sheep primordial follicle and its development in a two-dimensional followed by three-dimensional alginate system, co-cultured with theca progenitor cells to provide the interactive in vivo condition for development of follicles.MthodsThin sheep ovarian fragments of cortex were cultured for eight days in the presence of theca progenitor cells and ultimately examined for hormonal secretion, and expression of genes related to follicle and oocyte maturation. Subsequently, grown follicles were isolated from tissue and co-cultured with theca progenitor cells in a three-dimensional culture in 1% sodium alginate for 7 days, and evaluated for follicular morphology and growth.ResultsIn tissues co-cultured with TPCs, the percentage of follicles in sheep s ovarian tissue, hormonal activity, as well as the expression of growth and development related genes were significantly higher than control (P<0.05). Culture of isolated follicles in three-dimensional conditions for seven days showed that the diameter of the follicles increased after seven days, and the theca precursor cells showed radial arrangement around the follicles.ConclusionIn this study we could promote the primordial sheep follicle development via a two-step culture system with TPCs. In this system, growth of primordial follicles andregular array of TPCs around follicles could be observable.

Keywords:

Follicular activation and development , Theca progenitor cells , Three dimensional culture , Co-culture