Figure 9: IHC showed that micromass cartilage expressed aggrecan and COL VI at all the time points (weeks 1–4, a, b). Articular cartilage of rat knee expressed aggrecan and served as positive control (a). Human tracheal cartilage served as positive control for COL VI and showed that COL VI is pericellular in location in native cartilage (b). Higher magnification of week 4 bioengineered micromass cartilage also shows the pericellular localization of COL VI (arrowheads, b). Rat knee (a) and micromass cartilage (b) were used as negative control with rabbit IgG polyclonal and without primary antibody. M, meniscus; AC, articular cartilage; B, bone; mm, micromass.