Gross morphology, histology, and immunohistochemistry (IHC) of constructs and native articular cartilage. (A) The gross morphology from a top (row 1) and side view (row 2) of constructs after t=4 weeks of culture and native bovine articular cartilage is shown (ruler segments=1 mm). Histology sections were stained with toluidine blue to detect sulfated glycosaminoglycans (GAGs) (row 3). IHC was performed on sections for superficial zone protein (SZP) (row 4), type II collagen (row 5), and type I collagen (row 6) (scale bar: 100 μm). (B) Images of middle zone (MZ) constructs (0:100), surface zone (SZ) constructs (100:0), and native cartilage were enlarged to display chondrocyte morphologies (scale bar: 100 μm).