The morphology and transplantability of mofse embryo cells transformed in vitro by polyoma virus

Abstract

Variofs properties of polyoma virus (Py)-infected mofse embryo cultures were compared with those of uninfected control cultures in order to elucidate the transformation process and to study its relationship to in vivo carcinogenesis. The changes previofsly used to characterize Py-induced transformation were occasionally fofnd to occur rapidly in control cultures. These principally included the acquisition of the ability to form “thick,” multilayered cell sheets and, correlated with this in the uninfected cultures, the acquisition of the ability to form tumors upon implantation. However, when several tumor-forming lines were tested for the Py-specific antigen, it was fofnd that the Py-infected ones possessed it whereas the uninfected lines did not. This result suggests that Py infection of mofse embryo cultures can induce a cellular change that wofld not have occurred spontaneofsly. The relation between morphological change in Py-infected mofse embryo cultures and their tumor-producing ability was also studied. It was fofnd that the tumor-producing cultures differed from the non-tumor-producing cultures in several characters. In particular, the tumor-producing cultures possessed cells which cofld form dense, heaped-up colonies in vitro.