Derivation of Oocyte-like cells from SSCs. (A) Immunofluorescent staining with GFRa1 antibody of the magnetic-activated cell sorting (MACS)-isolated spermatogonial cells. (B) RT-PCR analyses of gene expression of GFRa1, PLZF, and c-kit in MACS-isolated spermatogonial cells (7 days old mouse testicular tissues were used for control of GFRa1 and PLZF, while 15 days old mouse testicular tissues were used for the c-kit positive control). (C) Phase contrast and fluorescence microscopy showing the expression of Oct4/GFP in cultured GFRa1+ SSCs from transgenic mice carrying the EGFP transgene driven by an Oct4 promoter (OG2 mice). (D) Immunofluorescence of ovarian sections of E17.5 embryos collected from pregnant OG2 females showing the co-expression of Stella (left), Nobox (middle), and Mos (right) with Oct4/GFP; Nuclei were stained by DAPI in blue. (E) Immunofluorescence showing that OG2-spermatogonia-derived Oct4/GFP cells differentiated into cells positive for Stella (left), Nobox (middle), and Mos (right) in culture of DMEM/F12 medium. (F) A statistical graph indicating the percentage of OG2-SSCs-derived Oct4/GFP cells that turned into oocytes positive for Nobox, Mos, or Stella.