Fig. 2. Growth rate analysis of cell lines established from midgestation embryos. Cell lines were established from the (A) aorta-mesenchyme, (B) urogenital ridges, (C) embryonic liver and (D) gastrointestinal tissues of embryonic day 10 and 11 mice. The number of cells in each culture was counted at each passage, and the total number of viable cells (calculated) is plotted against time (weeks in culture after initial plating). Black-filled symbols represent cell lines derived from the tsA58 transgenic embryos, and white-filled symbols represent cell lines derived from the control lacZ transgenic embryos. All cell lines and clones established from Tag5 and Tag11 transgenic embryos contained the tsA58 transgene as determined by PCR analysis.