Ovarian Somatic Stem Cells

Reproductive gonads and tracts are expected to vastly remodelduring mammalian life span, which lends credence to the essentialrole of somatic stem cell in regenerative cycle. Althoughthere is a continuous debate about the existence of oocyte derivedstem cell in adult ovary, the presence of somatic stem cellsto produce different parts of ovary have long been neglected.The ovarian surface epithelium (OSE) and cortex mainly originatefrom somatic ovarian stem cells. OSE are composed ofsmall number of cells that capable of self-renewing and differentiatinginto immature oocytes in vitro or in vivo. This quality,the capability of differentiation into two cell types and ovarianrepair during ovulation, would apparently make OSE conductiveto somatic stem/progenitor cell mediated processes investigation.Multipotent granulosa cell progenitors, as a source ofsomatic stem cells of ovarian cortex, can be differentiated intothree distinct lineages and have a prolonged life span in vitro.The theca layer is another source of somatic stem cells in theovarian cortex. Theca stem cells were isolated and purified fromneonatal mouse ovary in vitro. In granulosa cell-conditionedmedia, these cells show signs of differentiation, lipid droplet accumulation,smooth endoplasmic reticulum formation and later,production of androstenedione, Luteinizing hormone (LH), Insulin-like growth factor ۱ (IGF۱), and stem cell factors (SCF).Similar to in vivo conditions, the transplanted theca cells movedinto the mouse ovaries and were surrounded by the growing follicles.The cellular properties and the in vitro differentiation capacityof porcine ovarian theca-derived multipotent stem cellshave also been examined. There is no information in literature,regarding human theca stem cells (hTSCs) and their behaviorduring cell culture. We have isolated and characterized hTSCsand differentiated into human theca progenitor cells (hTPCs)and human oocyte like cells (hOLCs).