OBJECTIVEThe purpose of this study was to compare the morphological character between immortalized mandibular condylar chondrocyte (IMCC) and primarily cultured mandibular condylar chondrocyte (MCC).

METHODSThe phase contrast microscope, photomicroscope and transmission electron microscope were used to observe the morphological character of IMCC and MCC. The highresolution pathological image and word report system-1000 (HPIAS-1000) was used to compare the size of IMCC and MCC.

RESULTSThe phase contrast micrography showed that MCCs in primary culture underwent distinct morphological changes with respect to shape, size, and density of the cells. The majority of MCCs were in polygonal shape earlier in culture, while more fusi-form and spindle-shaped cells were found after 4-5 passages. While IMCCs were polygonal-shaped, similar to MCCs. Subculture, freezing and recovering had no effect on cellular shape of IMCC. Transmission electron microscopy indicated that MCC had chondrocyte-like phenotype, while IMCC looked like prechondroblast or immature chondrocyte. Some of IMCCs had irregular nucleus, and the proportion of nucleus/cytoplasm changed. By analysis of HPIAS-1000, the diameter and area of IMCC were obvious smaller than those of MCC (P < 0.01).

CONCLUSIONIMCC retain the main morphological character of MCC, and also keep a stable phenotype, which belong to immature chondrocytes, similar to cells in the proliferative zone.