Fig. 5

Chondrocyte apoptosis in osteochondral samples, as analyzed by TUNEL immunoassay to detec apoptotic cells. a Light microscopy images showing abundance of viable cells (green) in fresh cartilage and increased population of apoptotic cells (brown-black) after 14 and 28 days of storage in different conditions. Scale bar = 50 μm. b The percentage of apoptotic cells was calculated as the number of apoptotic cells related to the total number of cells. Apoptosis significantly increased throughout different storage groups. *p < 0.001 (fresh versus all other groups, except 4 °C after 14 and 28 days); #p < 0.05 (fresh versus 4 °C after 14 and 28 days); **p = 0.008