After cultivation in chondrogenic medium for 5 weeks, the dense cellular layer developed into physiologically stratified cartilage. A H&E, B Alcian Blue, C Collagen type II, D Lubricin, E Collagen type I, and F Collage type X. [Bar: 500µm] Image reproduced with permission from Bhumiratana et al., PNAS 111, 6940, 2014) (16).