Figure 3.

Gross morphology, histology and IHC of constructs at t = 5 wk (top) and native TMJ disc tissue (bottom). Shape-specific TMJ disc neotissue was treated with BM (passive axial compression), BA (C-ABC + TGF-β1), BM+BA, or left untreated (control). Engineered constructs were imaged with the middle zone on the left side of all images, transitioning into the band region toward the right, while entire middle zone and band region images were taken for native discal tissue. Collagen was stained using Picrosirious red and observed under polarized light to detect fibril organization and alignment. GAG was stained using Safranin O/Fast Green, while IHC was used to stain for collagen types I and II. BA and BM+BA treatments resulted in denser and more uniform collagen staining showing matrix alignment under polarized light, with enhanced organization observed in the combination-treated constructs. Like native TMJ disc tissue, BA and BM+BA neotissue stained negative for GAG. Finally, IHC found engineered neotissue to stain more strongly for collagen type II than type I, opposite of results for native tissue. Scale bar is 100 μm for histology, 150 μm for IHC, and the markings on the morphology images are 1 mm apart.