Effect of cell proliferation on the condensation of X chromosomes in the form of Barr-bodies, in human 46 XX fibroblast cultures with different serum concentrations]

The frequency of Barr-bodies in cultivated 46 XX human fibroblasts considerably increases when in confluent monolayer cultures the cells no longer divide. Or, independently of cell contact, when the cells are grown in medium with low serum content, which will slow down or entirely arrest further growth. The frequency of Barr-bodies again diminishes when after the administration of culture medium with sufficient serum concentration, the cells start growing again, indicating that the condensation of the X chromosome is reversible under control of the cell proliferation.