Fig. 2

Gross morphology and histology of one representative rabbit per group sacrificed 4 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 filled up with repair tissue, while in the treated ones the HA gel (e) or HA gel + matrix (f) is shown very well. g–i shows cross-section histology of the implantation site stained with safranin-O. In the untreated group (g) the highest proteoglycan staining (red) was detected. The HA gel group (h) shows a weak proteoglycan staining, while in the HA gel + matrix group (i) no proteoglycan was detected on the implantation site