The testing of stem cell marker expression. A, B. PTSCs and ATSCs at passages 10 expressed Oct-4, respectively. C. No Oct-4 staining was detected on tenocytes. D, E. PTSCs and ATSCs expressed SSEA-4. F. Tenocytes were negative for SSEA-4 staining. G, H. PTSCs and ATSCs expressed nucleostemin. Insets show enlarged view of expressed nucleostemin in pink (arrows). I. Nucleostemin expression was not detected on tenocytes. (bar: 50 μm).