Figure 1. Steroid receptor expression in purified OSCs. (A, B) Steroid receptor expression profile in OSCs from young adult (2-month-old) mouse ovaries by RT-PCR (A) and western blot analysis (B). Expression of β-actin is shown as a control for equality of sample loading; +RT and –RT represent PCR of RNA samples with and without reverse transcription, respectively (the latter used to rule out target gene amplification from potential genomic DNA contamination). Adult ovarian tissue was used as a positive control, as indicated, since all three steroid receptors under investigation (ERα, ERβ, PR) are widely known to be expressed in this tissue. (C–G) Flow cytometric analysis of ERα protein expression in extracellular Ddx4-positive OSCs. (C) ERα-negative control gate; (D) population shift for ERα-positive cells; (E) population shift for extracellular Ddx4-positive cells (see panel G for negative control gate); (F) extracellular Ddx4/ERα dual-positive cells, as shown in the upper right quadrant; (G) extracellular Ddx4-negative control gate. (H) Quantification of the percent of OSCs (extracellular Ddx4-expressing cells) dual-positive for ERα expression (93.8 ± 0.5%; mean ± SEM, n = 3 independent sorts).