Fig. 3

Expansion of OCT-4 positive stem cells upon endometrial scratching. Upper panel: OCT-4 expression in control uterus without any injury. OCT-4 positive progenitor cells were occasionally detected in the stromal and myometrial compartment. OCT-4 was not expressed by the mature differentiated epithelial and stromal cells. Lower panel shows increased expression of OCT-4 after 24 h of endometrial scratching. OCT-4 positive cells were activated in large numbers upon mechanically scratching the uterine lumen within 24 h. OCT-4 positive stem cells with both nuclear and cytoplasmic OCT-4 were clearly observed in large numbers in endometrial sections. Immune cells also accumulated at the injury site but remained negative for OCT-4 (i, ii, v, vi) while small-sized OCT-4 positive stem cells were observed in close vicinity at the injury site and helped to regenerate and maintain normal homeostasis (i–vi). OCT-4 positive stem cells came out from their quiescent state and expanded in large numbers to regenerate and regain homeostasis and wound healing. Scale: i–iv: 10 μm and v–vi: 5 μm