The availability of mice homozygous for the PrkdcSCID (severe combined immunodeficient mice) or mice with a mutation in the forkhead box protein N1 (FOXN1) gene (Nude mice; athymic with greatly reduced number of T cells) allows human endometrium to be xenografted either subcutaneously 75 or intraperitoneally 76 to generate humanized models of endometriosis because the mice do not mount a rejection response. Here, FOXN1 is linked to endometriosis.