Allogeneic refers to cells, tissues, or organs that are derived from a genetically different individual of the same species. This term is commonly used in medical contexts, particularly in transplantation, where an organ or tissue is taken from a donor and given to a recipient. The donor and recipient may be related or unrelated, but they must be compatible to reduce the risk of rejection. In bone marrow transplants, for example, an allogeneic transplant involves using stem cells from a donor to treat conditions like leukemia or other blood disorders. The success of allogeneic transplants often depends on the degree of genetic matching between the donor and recipient, which can influence the body's acceptance of the transplanted material.