Comparison of the urea cycle in conventional and germ-free mice

The urea cycle in the liver of conventional mice was compared with that of germ-free mice. Among the urea cycle enzymes and urea cycle-related substances, only ornithine in the liver of the conventional mice was markedly more abundant than in that of the germ-free mice. The significance of this finding was supported by the comparison of the urea synthesis in the liver slices from these two types of mice.