DIFFERENTIATION AND PROGRAMMED CELL-DEATH IN SA-45 TUMOR TREATED WITHBONE INDUCER

The relationship between differentiation and concerted cell death was studied using ultrastructural, histochemical and immunochemical method s in solid rat fibrosarcoma Sa-45 grown in the presence of demineraliz ed bone matrix. The control tumour consisted mostly of undifferentiate d cells with few poorly or moderately differentiated cells. In the pre sence of the inducer, cells with a more differentiated pattern appeare d in the surrounding area. The proliferative activity in the presence of the inducer was 3 to 5 times lower but the apoptotic index was high er than in the controls. However, complete differentiation was induced only in stromal cells, whereas the parenchymal cells showed signs of enhanced but incomplete differentiation. The ultrastructural signs of programmed cell death progressed in them faster than the corresponding features of maturation, thus leaving differentiation incomplete.