Dr. Kurt Benirschke, professor of reproductive medicine at the University of California at San Diego and a member of the Zoological Society of San Diego's Research Committee, had been discussing the idea of a scientific research arm of the organization with Dr. Charles Schroeder, Charles Bieler, and fellow committee members for several years. In the early 1970s the idea began to take shape, and in 1973 and 1974, Charles Bieler and Dr. Benirschke worked together on plans and fundraising for the new research center. On January 1, 1975, Dr. Benirschke assumed his duties as Director of Research for the Zoological Society, and the Center for Reproduction of Endangered Species (CRES) was officially launched. One of the initial projects for CRES was to establish a tissue bank that would preserve skin samples and sperm from a wide variety of animal species, to allow for the study of animals' chromosomes and to provide for potential artificial insemination. This would become known as the Frozen Zoo. Here, Dr. Benirschke shows some of the samples that were first preserved.