Fig. 3

Gross morphology and histology of one representative rabbit per group sacrificed 12 weeks after treatment. a–c shows the implantation site of the trochlea of the femur. d–f represents cross-section histology of the implantation site stained with hematoxylin and eosin (H & E). In the untreated group (d) the defect was observed with little tissue formation, while the HA gel (e) or HA gel + matrix (f) enhanced better repair tissue with adequate cell distribution (violet). g–i shows cross-section histology of the implantation site stained with safranin-O. In the untreated group (g) a high proteoglycan staining (red) was detected in the almost existing defect. The HA gel group (h) shows more proteoglycan staining, but not as much observed in the group treated with HA gel + matrix (i)