Fig. 4

Histological and immunohistochemical characterizations of pellets generated by osteoarthritic chondrocytes. a Safranin-O staining of baseline pellets and pellets after 2, 7, and 14 additional days of culture in control (CTR) medium or notochordal cell conditioned medium (NCCM). There is a clear increase in Safranin-O with NCCM treatment at 14 days of culture. Collagen type II (b) and collagen type I (c) immunostochemical staining of representative pellets after 14 days phase II culture in CTR medium or NCCM (see Fig. 1 for the experimental design). Bars = 100 μm. As with the Safranin-O staining, 14 days of NCCM culture induces a marked increase in collagen type II staining with no difference in type I collagen