MRL/MpJ (MRL) is a model mouse for autoimmune diseases that shows dermatitis, vasculitis, arthritis, and glomerulonephritis. In addition to these immune-associated disorders, we found that aged MRL mice develop ovarian cysts originating from the rete ovarii, which is lined by ciliated or nonciliated epithelium and considered remnants of mesonephric tubules. Ovarian cysts, which are reported to have several sources, are associated with female infertility, but information regarding the genetic etiology of ovarian cysts originating from the rete ovarii is rare. In this study, to elucidate the genetic background of development of ovarian cysts, we performed quantitative