Accumulation of DNA within chromocentres of terminally differentiating chick embryo chondrocytes

Automated television (TV) densitometric technique which allows the recognition and recording of chromatin compartments was applied to the study of chromatin rearrangement during chondrogenesis. Genetically active chondroblasts and inactive definite chondrocytes of E7 chick cartilage model, stained on the imprints for DNA, were a subject for the comparative study. Large chromatin granules with constant morphometric parameters, displaying positive staining for C-heterochromatin and identified as chromocentres, were found to accumulate 30% of cellular DNA, doubling its concentration during chondrogenic maturation. A test for the DNA content ethalonization proved this to be due to redistribution of DNA from the euchromatinic compartment.