3t3 cells are a tissue culture line developed from the fibroblasts of an embryonic albino Swiss mouse. First established in 1962, for the next twenty years 3t3 cells were principally used in the study of virus oncogenics.

View a second image of a mouse embryonic fibroblast cell culture.

View a third image of a mouse embryonic fibroblast cell culture.

Other cell lines were in use before 3t3 cells, but the newer culture line soared to the forefront of science because of its particular characteristics. Unlike other tissue cultures available at the time, 3t3 cells did not cause tumors when injected in mice. Careful study led to the discovery of the underlying cause, which is that the cells exhibit a highly developed inhibition of growth based on density levels. In fact, the behavior of 3t3 cells established an unambiguous distinction between the capacity to grow indefinitely and the ability to develop tumors.

Useful in a multiplicity of ways, 3t3 cells have been utilized for a wide variety of studies and experiments. One area of particularly heavy employment of the cells has been the study of endogenous retroviruses in rodents. However, the tissue culture has also been important to evolutionary biologists in their attempts to explain speciation and to genetic engineers interested in placing foreign genetic material into new organisms to attain desired traits.