2010年考研英语阅读理解专项练习003[1] 2010年考研英语阅读理解专项练习003[1]

The transplantation of functioning human immune systems into mice was reported by two California research teams in September 1988.The mice should have many important uses in medical science,such as enabling researchers to test treatments against a number of diseases and to study the effects of infectious microorganisms-including the AIDS virus-on the human immune system.

　　Both research groups-at the Medical Biology Institute in La Jolla and at Standford University-started with a special strain of mice that are without an immune system.The La Jolla scientists injected the mice with human B cells and T cells,white blood cells that are major components of the immune system.The cells reproduced in the mice’s bodies and migrated throughout the animals’circulatory systems.

　　The Stanford researchers implanted human fetal lival tissues,thymusgland tissues,and lymph nodes,into the mice.In the mice’ bodies,the liver cells produced stem cells,which develop into the various kinds of blood cells.The implanted tissues converted the stem cells into B cells and T cells.

　　The mice with immunesystem transplants by both research teams were fully protected against infectious disease.Ordinarily,mice of the strain used by the scientists die soon after birth unless they are kept in a sterile(无菌的)environment.