in order to determine whether the differentiated phenotype was maintained on composite gels , we compared the levels of messenger rnas for cartilage-specific proteoglycan , link protein , alpha 1 ( ii ) and alpha 1 ( i ) collagens in chondrocytes grown at low density on composite gels or at high or low density on tissue culture plastic for up to 21 days .
C0007301
cartilage
C0225369
chondrocytes