Fig. (3) Meniscus tissue from OA patients (n=15) stained with alizarin red (A, B) and eosin Y (C, D). Alizarin red stains for all calcium crystals in comparison to eosin Y, which only stains for CPPD crystals under polarizing light microscopy. White arrows represent eosin Y positive CPPD crystals, while black arrows represent calcium crystals that are positive for alizarin red and not eosin Y (BCP). Scale bar = 500 µm (top), 200 µm (bottom).