FIG. 7.

Histological and immunohistochemical staining of ACL sections. Pieces of at least n=10 torn and intact ACLs were analyzed and representative images are shown. (a) H&E staining revealed ACL cells within the tissue matrix, as well as the vessel walls. Azan and M/G staining was used to illustrate the density and organization of the collagen fibers that form the tissue matrix within which the ACL cells are embedded. (b) Immunolocalization of antigens CD44, CD90, CD105, and STRO-1 revealed positive cells within the fascicles of the ACL, as well as the endothelium of the vasculature. Examples of such cells are denoted by white (fascicles) and black (endothelium) arrows, respectively, in 500×panels. This indicates that ACL-derived mesenchymal stem cells are likely to originate from both the bulk fascicle tissue as well as the small vessel walls of the ACL. Scale bars: 100×bar=200 μm; 200×bar=100 μm; 500×bar=40 μm. Color images available online at www.liebertonline.com/tea