Future perspectives in the development of new animal models.

It is essential to develop animal models for human diseases with disease onset mechanisms the same as those of humans to study the causes, and therapeutic and preventive methods for human disease, as well as to develop new drugs. In the past, many beneficial experiments were performed by selecting animals with symptoms similar to those of humans from nature or breeding colonies. Experimental systems using induced disease models have been developed and provided useful results. The current basis of biology has reached the molecular level, and various phenomena of life have come to be understood through clarification of the expression of genes (DNA). Human diseases are one of these life phenomena, and the study of the relation between life phenomena and genes (DNA) has already started in the field of genetics. The next step appears to be the manipulation of genes to produce animal models for various human diseases. Progress has already been made in genetic and cellular engineering and embryonic manipulation on the basis of their respective methodologies and principles. One of the topics for future studies will be the development of models for human diseases through the integrated application of these fields. It is clear from documents on medical history that experiments using animals have been performed from the earliest period of ancient medical research. Therefore, pioneers in each period continued such studies and by the time of Claude Bernard, animal experiments had become an essential part of medical research. He stated in 1865 in his "Introduction to the Study of Experimental Medicine" that "I not only conclude that experiments made on animals from the physiological, pathological and therapeutic points of view have results that are applicable to theoretic medicine, but I think that without such comparative study of animals, practical medicine can never acquire a scientific character." Following this, animal experiments were widely performed in all fields of medical research, but the animals used in such experiments were only improved to the level they have reached today through the modernization movement which started in Europe, the United States and Japan from the end of the 1940's through the beginning of the 1950's. From the 1960's, the term "biomedical research" came into use in the United States to describe experiments using animals in the fields of medical research.(ABSTRACT TRUNCATED AT 400 WORDS)