Microscopy of microfibrillar collagen-treated defects at 17 days post-surgery. Microfibrillar collagen-treated adjacent 5 μm demineralized bone sections stained with H&E (upper) and Trichrome-EVG at ×2 (left) and ×10 magnification. The edge of the defect is identified with black/green arrows, and the area of magnification shown with a dotted box. Defects show minimal healing with no evidence of newly formed woven bone. Dense bundles of residual collagen are observed (yellow arrows) and early fibrotic tissue within the marrow space (white stars). Blue stars indicate native collagen meshwork within the marrow space.