Updated results on the karyology of the WI-38, MRC-5 and MRC-9 cell strains.

Data concerning cumulative results obtained from studies of the karyology of the characterized MRC-5 cell strain and the MRC-9 strain at present being characterized, indicate that these cells have karyological characteristics similar to each other and to the extensively studied WI-38 cell strain. The general inference from these studies is that the cells are karyotypically stable and that their karyological characteristics are within the limits recommended for normal cell populations.