Figure 4.

Bright-field images of scaffold cross sections stained for mineral at equivalent positions for low, medium and high mineral content. Unmineralized (left column), SBF + Fet-mineralized (middle column) and SBF-mineralized (right column) were stained with von Kossa to indicate mineral content in brown. SBF-mineralized collagen shows a sparse population of stained crystals within the collagen bulk but a thick coating of mineral on the outer boundaries of the collagen surface, supporting the expectation that incubation in SBF without fetuin resulted primarily in surface mineralization. In contrast, SBF + Fet-mineralized collagen showed significant staining through the depth of the matrix, suggesting that incubation in fetuin-doped SBF resulted in mineral deposition within the collagen bulk. However, staining in this group was localized to the outer two-thirds of the matrix cross sections with the highest mineral concentration nearest to the outer edges of the scaffold. No positive staining was seen in the Unmin matrices (the dark top surface of the Unmin group is a result of matrix folding during handling and prior to sectioning). Scale bars for bright-field images are 50 µm. (Online version in colour.)