CELLULAR ELEMENTS IN GIANT CELL TUMOR OF BONE FEULGEN-DNA QUANTITATION, 3H_TdR INCORPORATION AND ULTRASTRUCTURE OBSERVATION

Anti-erythrocyte rosette assay was used to sub divide stromal cells (StCs) of cultured giant cell tumor (GCT) of bone into two groups, the rosette forming cells (RFCs) and non-rosette forming cells (NRFCs). Characteristics of Feulgen-DNA content, 3H.TdR uptake and ultrastructure of different cellular elemcnts in GCT were then investigated by micro- spectrophotometry, autoradiography and both TEM and SEM. Two types of StCs and multinucleated giant cells (MGCs) showed 2C DNA stem line, which contrasted strikingly with aneuploid DNA in osteosarcoma cells. Autoradiography revealed that the labelling index of NRFCs increased with the time of 3H.TdR incorporation in vitro, while RFCs and MGCs were scarcely tagged. The two types of StCs were distinctly different in both surface and intra- cellular structures. The phagocytic function and sur- face appearance of RFCs resembled those of ma crophages, and no polymorphism was found in RFCs. These facts suggest that NRFCs are the neoplastic element in GCT, whereas RFCs are the end-stage cells and possibly the macrophages related to tumor immunity.