title: Intrapelvic injection of menstrual endometrium causes endometriosis in baboons (Papio cynocephalus and Papio anubis).
abstract: OBJECTIVE
  The Sampson hypothesis of retrograde menstruation as a cause of endometriosis was tested by determining the effect of intrapelvic injection of menstrual versus luteal endometrium on the incidence, peritoneal involvement, and stage of endometriosis.
  
  
  METHODS
  Seventeen baboons were injected retroperitoneally with luteal (n = 6) or menstrual (n = 7) endometrium and intraperitoneally with menstrual endometrium (n = 4). Laparoscopies were performed after 2 months in all animals and after 5 and 12 months in six and five primates injected with luteal and menstrual endometrium, respectively.
  
  
  RESULTS
  The peritoneal endometriosis surface area, number of implants, and incidence of typical and red subtle lesions were significantly higher after retroperitoneal injection of menstrual than of luteal endometrium. By use of menstrual endometrium intraperitoneal seeding was more successful in causing endometriosis than was retroperitoneal injection. No significant changes in number or surface area of endometriotic lesions induced with retroperitoneal injection of luteal endometrium after 5 months were observed in the six baboons. At repeat laparoscopy 12 months after intrapelvic injection of menstrual endometrium progression was recorded in three of four regularly cycling animals, whereas regression was evident in one baboon that had become amenorrheic after induction.
  
  
  CONCLUSIONS
  Intrapelvic injection of menstrual endometrium can cause peritoneal endometriosis and offers experimental evidence supporting the Sampson hypothesis.
authors.affiliation: Institute of Primate Research, Nairobi, Kenya.
authors.forename: T M
authors.initials: TM
authors.lastname: D'Hooghe
authors.forename: C S
authors.initials: CS
authors.lastname: Bambra
authors.forename: B M
authors.initials: BM
authors.lastname: Raeymaekers
authors.forename: I
authors.initials: I
authors.lastname: De Jonge
authors.forename: J M
authors.initials: JM
authors.lastname: Lauweryns
authors.forename: P R
authors.initials: PR
authors.lastname: Koninckx
mesh_terms: D000818:Animals; D004715:Endometriosis / Q000209:etiology* / Q000473:pathology; D004717:Endometrium / Q000637:transplantation*; D005260:Female; D007267:Injections; D007274:Injections, Intraperitoneal; D010535:Laparoscopy; D008183:Luteal Phase / Q000502:physiology; D008598:Menstruation / Q000502:physiology*; D010215:Papio; D010388:Pelvis; D014184:Transplantation, Homologous