Fig. 4. Competitive PCR analysis of vas and -tubulin expression in a co-culture of dissociated testicular cells with ZtA6 feeder cells and in a culture of dissociated testicular cells alone. Co-culture was used with cDNA from a co-culture of dissociated testicular cells with mitomycin C-treated ZtA6 cells. The control used cDNA from dissociated testicular cells cultured alone plus the same ZtA6 cells as that used in the co-culture cultured separately, making it equivalent to the co-culture. Two hundred times more vas cDNA was used than -tubulin cDNA. As duplicate experiments resulted in the same pattern, this figure shows the results from one experiment. The number below the photos indicates the ratio of sample density to competitor density.