Todaro created the BALB/3T3 clone A31 cell line in 1968 from disaggregated 14- to 17-day-old BALB/c mouse embryos.
Some evidence suggests that these cells are multipotential mesenchymal cells that can differentiate into different tissues in response to different microenvironmental influences or culture conditions.
Mouse embryo cells grown in culture are likely to become permanent cell lines.
Repeatedly transferred before confluence to minimize cell-cell contact, the emerging lines are susceptible to contact inhibition of cell division, grow at a high dilution, and exhibit a low saturation density.
These cells have a karyotype with a modal number of 78 and a range of 62 to 109.
The majority of the cells only had telocentric or acrocentric chromosomes.
Some cell lines have been reported to have cytogenetic instability in the literature.
Although the BALB/3T3 clone A31 cells are not tumorigenic, they exhibit tumorigenic properties in a semisolid medium.
In tissue culture, these cells are highly susceptible to transformation by the oncogenic DNA virus SV40 and the murine sarcoma virus.
They were also tested for ectromelia virus and found negative (mousepox).
