title: The embryo as allograft.
abstract: The main problems and experimental results with respect to the mechanism by which the embryo, as "allograft", is tolerated within the maternal organism are reviewed. The following hypotheses are discussed: the immunological "immaturity" of the embryo and of its appendages; the immunological incompetence of the maternal organism; the uterus as an immunologically "privileged" area; the existence of an immunological barrier between the mother and the embryo.
mesh_terms: D000818:Animals; D004622:Embryo, Mammalian / Q000276:immunology*; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D011247:Pregnancy; D051381:Rats; D014184:Transplantation, Homologous; D014327:Trophoblasts / Q000276:immunology; D014599:Uterus / Q000276:immunology