Application of the Barr and Stround GN5 densitometer for description of the chromatin structure

Nuclei isolated from rat liver can be separated in non-parenchymal diploid, parenchymal diploid and tetraploid nuclei. These nuclei are studied in their chromatin structure using a Barr and Stroud GN5 integrating densitometer. The measuring instrument has the possibility to read an integrated absorbance and as a second value the area of an absorbing object at different levels of extinction. The projection area of Feulgen-stained nuclei were measured at 557 nm at different extinction levels. From the results the conclusion can be drawn that the chromatin structure of parenchymal diploid and tetraploid nuclei is quite the same, however, the chromatin structure of non-parenchymal nuclei is more condensed. This method can be applied for an objective description of the pattern of chromatin density.