In general, the mature chondrocytes are characterized by a rounded morphology and
the production of cartilage extracellular matrix such as type II collagen and aggrecan.However, articular chondrocytes isolated from rat were limited in number. Therefore, chondrocyte expansion in monolayer condition was necessary before cultivation on the tested scaffolds. Unfortunately, the monolayer expansion causes dedifferentiation of
chondrocytes as shown by a fibroblastic morphology accompanied by loss of type II collagen expression [38-41]. Fibroblasts are characterized by flattened shapes and theexpression of type I collagen. Thus, re-differentiation and restoration of the chondrocytic phenotype during the cultivation period is crucial.