<prompt> Skin transplant was done from sister to brother. After few years, brother to sister skin transplant was done, but rejection occurred. This phenomenon is known asEichwald silmser effectSchultz Dale phenomenaTheobald smith phenomenaSchwazman reaction  <response>: Eichwald-Silmser effect, which is a unilateral sex-linked histoincompatibility. While transplants between same sex siblings are successful, grafts from female to male are also successful, but an exception is seen when the donor is a male and the recipient is a female. Such grafts are rejected as the grafted male tissue XY will have antigens determined by the Y chromosome which will be absent in the female XX recipient. Reference: Ananthanarayan and Paniker;s Textbook of Microbiology Tenth edition 