RESUMO
The dispersion of the chromosome number was studied in a rat liver cell line which was grown up to the 65th passage in our standard culture medium (Ham F10 containing 10% fetal calf and 10% adult human sera) and thereafter cultured in the same chemical medium supplemented with decreasing serum concentrations. Until the serum concentration changes, the parental cell line exhibited for several passages a very wide range of chromosome numbers, from 35 up to 83. This range narrowed down to 42 when the cells were passed in a 5% fetal calf serum medium. Then, after several passages in this 5% serum medium, when subculturing again in 20% serum, a second cell population, hypotetraploid, progressively appeared until a compound population, hypotetraploid, progressively appeared until a compound population reached a 45-80 bimodal state. Another sub-line grown in 1% fetal calf serum exhibited similar chromosome evolution but returned to a slight aneuploid state (43 chromosomes) in media supplemented with 20% serum of different types.
