Histologic features of human meniscal cells cultured in 3D collagen sponge in the presence of TGF-β. A, note the high cell density; B, note accumulations of ECM marked by *. (Paraffin embedded sections stained with toluidine blue; for both images, bar = 50 μm).
Gruber et al. BMC Biotechnology 2008 8:54 doi:10.1186/1472-6750-8-54