ences in some experiments. For breeders: Understanding (1) the reasons quality is required for laboratory animals, (2) the necessity of using objective scientific evidence to evaluate colonies, and (3) which procedures to use to confirm the genetic quality of laboratory animals.

Finally, in animal experiments (especially safety studies) using closed colonies, I recommend collecting and preserving DNA or biochemical marker data for tests on animals (mice and rats) used in safety studies in the development process of a new drug. If the results obtained in a safety study show significant differences from those obtained in a previous study or from other institutions, the causes can be narrowed down to the following: techniques (such as method of administration), environment (such as food, including temperature and humidity), and/or animals (genetic differences between the colonies used in the studies). Techniques and environment are specified in the GLP, as mentioned; but for animals used in the studies, only the strain names remain. It is important to know the genetic composition of the individuals that comprise the colonies used in the studies if the data obtained are to be utilized effectively. I therefore recommend that the genetic test data obtained for the animals used in such studies be preserved for future reference.

Katoh, H., S. Wakana, M. Ebukuro, and T. Nomura. 1998. Existence of outbred substocks demonstrated using genetic monitoring system. Rat Genome 4:120-125.

Nomura, T., K. Esaki, and T. Tomita, eds. 1984. ICLAS Manual for Genetic Monitoring of Inbred Mice. Tokyo: University of Tokyo Press.