Telomerase is an enzyme that regulates the lengths of telomeres in the cells of many organisms, and in humans it begins to function int the early stages of embryonic development. Telomeres are repetitive sequences of DNA on the ends of chromosomes that protect chromosomes from sticking to each other or tangling. In 1989, Gregg Morin found that telomerase was present

During the twentieth and twenty-first centuries, Robert Paul Lanza studied embryonic stem cells, tissues, and endangered species as chief scientific officer of Advanced Cell Technology, Incorporated in Worcester, Massachusetts. Lanza's team cloned the endangered species of gaur Bos gaurus.

At the turn of the twentieth century, Edmund B. Wilson performed experiments to show where germinal matter was located in molluscs. At Columbia University in New York City, New York, Wilson studied what causes cells to differentiate during development. In 1904 he conducted his experiments on molluscs, and he modified the