[Proliferative activity of cultures of embryonic mouse fibroblasts, infected by CA7(C8) adenovirus in a non-serum medium].

Primary monolayer cultures of mouse fetal cells were grown in serum-depleted medium. Cell proliferation parameters were measured by scanning cytophotometry and 3H-thymidine autoradiography. Both 1 h and 24 h thymidine labelling indices (LI) were extremely low in cultures growing without serum for 1 day indicating only residual proliferative activity. The number of cytophotometrically detected S-phase cells was slightly higher than the corresponding LI values. This suggests either the arrest of the cells in S-phase or failure to utilize exogenous thymidine without serum. 24 h after infection by oncogenic adenovirus SA7 (C8) a burst of proliferative activity was revealed in serum-depleted cultures with a dramatic increase of both LI values and the amount of S-cells detected by cytophotometry. These data are discussed in terms of possible virus-induced neoplastic cell transformation.