[Compared cytologic study of (in situ and isolated) metaphasic chromosomes from KB cells, after incorporation of 5 bromodeoxyuridine (5 BrdU)].

Substitution of thymidine by 5 BrdU indduces the same morphological and cytological changes in in situ and isolated metaphase chromosomes of KB cells: a dichroïc fluorescence and a difference in the affinity of each chromatid for Giemsa stain. However, the precursor does not seem to modify the appearance of G or Q bands in in situ and isolated chromosomes. The fibrilar unit which can be seen with electronic microscopy, shows no difference before and after 5-BrdU incorporation.