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. 2021 Mar 17;9:19. doi: 10.1038/s41413-021-00140-6

Fig. 5.

Fig. 5

Osteoclast resorption of bony interspinous ligaments releases active TGF-β to drive the progression of ossification in AS patients. a Hematoxylin and eosin (H&E) staining and b Safranin O–Fast Green staining of normal and HO-formed interspinous ligaments. In the AS group, the right panels show magnified views of the boxed area in the left panels. Scale bar: 100 μm (two panels on the right); 25 μm (two panels on the left). c Tartrate-resistant acid phosphatase (TRAP)-positive cells (red) and d quantitative analysis of the TRAP-positive osteoclast surface (OCS) per bone surface. The bottom panels show magnified views of the boxed area in the top panels. Scale bar: 100 μm (top panel); 25 μm (bottom panel). e Immunostaining and f quantitative analysis of CD68-positive cells (brown) in the normal and HO-formed interspinous ligaments (sagittal view). The bottom panels show magnified views of the boxed area in the top panels. Scale bar: 100 μm (top panel); 25 μm (bottom panel). g Immunostaining and h quantitative analysis of pSmad2/3-positive cells in the normal and HO-formed interspinous ligaments (sagittal view). The bottom panels show magnified views of the boxed area in the top panels. Scale bar: 100 μm (top panel); 25 μm (bottom panel). i Immunostaining and j quantitative analysis of Osterix-positive cells (brown) in the normal and HO-formed interspinous ligaments (sagittal view). The bottom panels show magnified views of the boxed area in the top panels. Scale bar: 100 μm (top panel); 25 μm (bottom panel). k Immunostaining and l quantitative analysis of PDGF-BB-positive cells in the normal and HO-formed interspinous ligaments (sagittal view). The bottom panels show magnified views of the boxed area in the top panels. Scale bar: 100 μm (top panels); 25 μm (bottom panels). m CD31-positive (red) cells, n EMCN-positive (green) cells and quantification of the fold change of o CD31-positive vessels, p EMCN-positive vessels in the normal and HO-formed interspinous ligaments (sagittal view). q PGP9.5-positive (red) cells and CGRP-positive (green) cells and quantification of the fold change of r PGP9.5 and CGRP double positive nerves in the normal and HO-formed interspinous ligaments (sagittal view). s Immunostaining and t quantitative analysis of pSmad1/5/8-positive cells (brown) in the normal and inflammatory interspinous ligaments (sagittal view). The bottom panels show magnified views of the boxed area in the top panels. Scale bar: 100 μm (top panels); 25 μm (bottom panels)