Fig. 2. Effects of retinoic acid pretreatment on the shape of cultured chondrocytes in the presence or absence of ConA. Poorly differentiated chondrocytes were not exposed to retinoic acid for 4 days and then incubated in the absence (A) or presence (B) of 5 µg ml^–1 ConA for 24 hours. Poorly differentiated chondrocytes were exposed to retinoic acid at 10^–6 M for 4 days and then incubated in the absence (C) or presence (D) of 5 µg ml^–1 ConA for 24 hours. Poorly differentiated chondrocytes were exposed to retinoic acid at 10^–6 for 4 days and then incubated in the absence (E) or presence (F) of 5 µg ml^–1 ConA for 72 hours. Bar, 30 µm.