Ovarian surface epithelium stem cells and in vitro developed oocyte-like cells in postmenopausal women. (A) Putative stem cells proliferating and growing in the cluster of scraped OSE cells (inverted microscope, Hoffman illumination, magnification 400x). (B) Putative stem cell and erythrocyte (inverted microscope equipped with Nikon Digital Sight DS-Ri1 camera, DIC-Nomarski illumination, magnification 6000x). (C) Oocyte-like cell without zona pellucida with attached putative stem cells possibly acting as granulosa cells (inverted microscope, Hoffman illumination, magnification 200x). (D) Oocyte-like cell with zona pellucida-like structure attached to the dish bottom (inverted microscope, Hoffman illumination, magnification 200x). (E) Blastocyst-like structure with blastocoel-like cavity at the beginning of "hatching"(inverted microscope, Hoffman illumination, magnification 100x). (F) Blastocyst-like structure after "hatching" (inverted microscope, Hoffman illumination, magnification 100x) (images: University Medical Centre Ljubljana, 2009).