Pathogenesis of Early-Onset Endometriosis

Offizielles Organ: AGRBM, BRZ, DVR, DGA, DGGEF , DGRM, D·I·R, EFA, OEGRM, SRBM/DGE Krause & Pachernegg GmbH, Verlag für Medizin und Wirtschaft, A-3003 Gablitz Journal für Reproduktionsmedizin und Endokrinologie – Journal of Reproductive Medicine and Endocrinology – Andrologie • Embryologie & Biologie • Endokrinologie • Ethik & Recht • Genetik Gynäkologie • Kontrazeption • Psychosomatik • Reproduktionsmedizin • Urologie Indexed in EMBASE/Excerpta Medica/Scopus www.kup.at/repromedizin Online-Datenbank mit Autoren- und Stichwortsuche Pathogenesis of Early-Onset Endometriosis Benagiano G, Gargett C, Brosens I J. Reproduktionsmed. Endokrinol 2015; 12 (4), 227-231 20.-21. März 2026 Universitätsmedizin Mainz ENDOKRINOLOGIE & FERTILITÄT FÜR KLINIK & PRAXIS Weitere Informationen & Anmeldung unter Einladung zu unserer wissenschaftlichen Veranstaltung Endo-Ferti-Forum Brücke(n) zwischen Unikliniken und Praxen an Rhein und Main(z) – die aus dem bisherigen Format „Ferti Forum“ ab 2026 hervorgeht – Freuen Sie sich auf spannende Vorträge und den lebendigen Austausch mit Kolleg:innen und Expert:innen aus Klinik und Praxis. Freitagabend laden wir Sie herzlich zu einem entspannten Empfang ein – eine perfekte Gelegenheit, Kontakte zu knüpfen und den T ag genussvoll ausklingen zu lassen. Wissenschaftliche Leitung: Univ.-Professorin Annette Hasenburg, Dr. Susanne Theis, Universitätsmedizin Mainz, Sanitätsrat Dr. Werner Harlfinger, BVF Rheinland-Pfalz Dr. Rüdiger Gaase, BVF Hessen Dr. Klaus J. Doubek Schirmherrschaften: Prof. Nicole Sänger, Uniklinik Bonn, Prof. Jan-Steffen Krüssel, Uniklinik Düsseldorf, Dr. Annette Bachmann, Uniklinik Frankfurt am Main, Prof. Christine Skala, Uniklinik Köln 227J Reproduktionsmed Endokrinol_Online 2015; 12 (4) Pathogenesis of Early-Onset Endometriosis G. Benagiano1, C. Gargett2, J. J. Brosens3, I. Brosens4 Three main theories have been put forward to explain the pathogenesis of endometriosis, that of a retrograde menstrual transpla ntation, that of an induc- tion of endometrial cells, and that of an in situ development. These hypotheses belong to two main groups: those proposing that implants originate from the endometrium and those advocating an origin from extra-uterine tissues. More recently, the discovery that stem/progenitor cells from bone marrow can dif- ferentiate into endometrial cells suggests a novel pathway through which these cells may colonize peritoneal and extra-peritoneal organs and differentiate into ectopic endometrium. On the other hand, for early-onset endometriosis a different pathogenetic mechanism may be in place. The possibility exists that in neonates endometrial cells and stroma are retrogradely disseminated in the pelvis, thanks to the presence of uterine bleeding, either visible or occult. Since menstrual desquama- tion causing neonatal bleeding may contain endometrial stem cells, they may in turn be responsible, through a variety of mechanisms, for early onset endo- metriosis. J Reproduktionsmed Endokrinol_Online 2015; 12 (4): 227–31. Key words: endometriosis, endometrium, adenomyosis, neonatal uterine bleeding  Introduction The first descriptions of what were ini- tially designated as “mucosal invasions of peritoneal organs”, namely the condi- tions we call today adenomyosis and en- dometriosis, date back more than a hun- dred years and by the end of the 19 th cen- tury they were given a common name, that of “adenomyoma” [1]. In spite of intensive research, even today these two diseases deserve the appella- tive of “elusive”, utilised by Emge [2] and Bird et al [3] to describe adenomyo- sis and endometriosis respectively, back in the nineteen sixties and seventies. Elu- sive, because the exact pathogenetic mechanisms are still incompletely un- derstood and the diagnosis often made after considerable time. In the early days of the 20th century, re- searchers concentrated on the histogene- sis of adenomyomas. Intriguingly, C. Rokitansky, the first to describe a case of what we would identify today as an “adenomyomatous polyp”, immediately recognised the endometrial nature of the epithelial cells found in the lesion. He mentioned that in a number of autopsies of women he found “fibrous polyps of the uterus” and that “among them there are some, in which glandular tubes are found” [4]; having found them protrud- ing from the endometrium, he correctly identified the “glandular tubules” as of endometrial nature. Unfortunately, his scientific publication carries the title “On the neoplasm of uterus glands and uterine and ovarian sarcomas”, and this seems to have distracted his contempo- raries from the significance of his work. Indeed, ignoring Rokitansky’s conclu- sions, during the second part of the 19 th century many pathologists argued that “adenomyomas” were the result of dis- placement of Wolffian or mesonephric vestiges; the most famous among them was F. D. von Recklinghausen [5]. They rejected the possibility that the glands they discovered as invading peritoneal organs were “endometrial” and opted for an embryologic origin. The first clear description of the morpho- logical and clinical picture of adenomyo- ma was made by T. Cullen. In his book “Adenomyoma of the Uterus” [6] he de- scribes an observation made in 1882 and clearly mentions that “the uterine muco- sa was at many points flowing into the diffuse myomatous tissue”. Cullen’s the- ory was dismissed for years and it was only during the second decade of the 20 th century that it finally gained acceptance [7] and, by 1920, most researches agreed that the epithelial cells and stroma in an adenomyoma were of endometrial na- ture. Once, the histogenesis was determined, it remained to clarify the pathogenesis of adenomyomas. This however, would only be possible once a relationship was found with another condition initially called “chocolate cysts of the ovary”, or “ovarian haematomas”, the ovarian en- dometrioma. The presence of endometrial glands and stroma in an ovary was first mentioned by W. W. Russel [8] in 1899 in a pre- menopausal woman who underwent sur- gery for a cystic adenocarcinoma of the left ovary. Opening the abdominal cavity, Russel found the right ovary enveloped in adhesion of the posterior face of the broad ligament and at microscopic ex- amination a number of areas were ob- served that “were an exact prototype of the uterine glands and interglandular connective tissue”. In line with the theo- ries of the time, Russel believed that the “tumor” was due to the presence of “ aberrant portions of the Müllerian duct” in the ovary. A number of addi- tional descriptions of “haematoma of the ovary” and of “chocolate cysts of the ovary” were also published at the begin- ning of the 20 th century [1]. Then, in 1921, J. Sampson published the first of his articles on the condition he later named “endometriosis”, describing 23 cases of “ovarian haematomas of endo- metrial type” [9]. Initially, he preferred to call the cyst’s epithelium “Müllerian”, because he felt that in some cases the epi thelium lining these ovarian ‘haema- tomas’ or ‘cysts’ may have been derived from the tubal epithelium. Sampson For personal use only. Not to be reproduced without permission of Krause & Pachernegg GmbH. Received and accepted: January 27th, 2015. From the 1Department of Gynecology-Obstetrics and Urology, Sapienza University, Rome, Italy; 2The Ritchie Centre, Hudson Institute of Medical Research and Department of Obstetrics and Gynecology, Monash University, Australia; 3Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratories, University Hospital, Coventry, UK, and the 4Catholic University Leuven, Leuven Institute for Fertility and Embryology, Leuven, Belgium Correspondence: Professor Giuseppe Benagiano, MD, Department of Gynecology-Obstetrics and Urology, Sapienza University, Piazzale Aldo Moro 5, I-00185 Rome, Italy; e-mail: [email protected] Pathogenesis of Early-Onset Endometriosis 228 J Reproduktionsmed Endokrinol_Online 2015; 12 (4) quickly developed a theory whereby the ovary would act as an incubator in the development of pelvic implantation of adenomas of the endometrial type [10]. Finally, in 1927, Sampson detailed his theory that the rupture of the endometrial cyst was the cause of peritoneal endome- triosis [11], whereas several authors pro- posed the opposite mechanism, namely that endometriotic lesions on the perito- neum moving to the cortex invaded the ovary, or that endometrial cells arrived inside the ovary via lymphatic vessels [12]. It was only in 1957 that P. E. Hughesdon demonstrated histologically in ovaries with chocolate cysts in situ that in 90% of the cases the wall of the cyst originated from invaginated ovarian cortex, but was frequently modified by cortical fibrosis and smooth muscle metaplasia of the inner cortex obscuring the presence of follicles in the deeper layers [13]. In the meantime, O. Frankl had developed his theory that adenomyo- mas growing within the uterine wall were a distinct entity which he named “adenomyosis” [14]. At this stage, endometriosis and adeno- myosis became known as different noso- logical entities with allegedly a different pathogenesis and, for decades to come, the two were considered independent diseases.  Adult Endometriosis Over the years, Sampson’s theory of a retrograde menstrual origin of endo- metrio sis [11] gained acceptance and is today the most widely accepted hypoth- esis for its existence. Nonetheless, the presence of various forms of endometri- osis (peritoneal superficial, deep, ovarian and extra-peritoneal) have led some to believe that they constitute separate noso logical entities [15] and therefore that their pathogenesis may present dif- ferent connotations. In 1980, Simpson et al [16] and Malinak et al [17] were the first to explore genetic and familial aspects of endometriosis and found that female siblings of sub- jects with histologically proven endome- triosis are almost 7-times more likely to develop the disease than women without a family history of endometriosis. To ex- plain their findings they opted for a poly- genic/multifactorial aetiology and con- cluded that an apparently healthy woman with an affected first-degree relative would have a 7% chance of developing endometriosis. Aberrant gene expression in endometriosis is not confined to the ectopic lesions but is also apparent in the eutopic endometrium [18–20]. In this re- spect, it is more and more evident that the characteristics of the endometrium play a key role in the complex sequence of events leading to the adherence of nests of endometrial cells and stroma to the peritoneum, its acquisition of a blood supply and ultimately its survival. Recently, Burney and Giudice [21] ex- pressed the opinion that theories regard- ing the pathogenesis of endometriosis can be reduced to two main groups: those proposing that implants originate from the endometrium and those advocating an origin from extra-uterine tissues. This is indeed the prevailing view of this enig- matic disease today. Some 10 years ago, Nap et al [22] re- viewing the subject concluded that 3 the- ories on the pathogenesis of endometrio- sis seem the most acceptable: the retro- grade transplantation, the induction and the in situ development theories. The Retrograde Menstruation Theory As mentioned, today the most widely ac- cepted hypothesis for the genesis of en- dometriosis is that presented by Sampson in 1927, i. e. peritoneal endometriosis is caused by retrograde dissemination and implantation of endometrial tissue frag- ments into the peritoneal cavity at the time of menstruation [11]. Years later Sampson [23] presented a complete ver- sion of his theory, specifying that in women with patent tubes, fragments of endometrial tissue are retrogradely trans- ported into the peritoneal cavity where, under facilitating conditions, they are able to adhere to peritoneal mesothelial cells and establish a blood supply that enables them to survive and proliferate. A number of observations support the re- flux theory, from the distribution of the lesions in the abdominal cavity, to the in vitro proven viability of shed menstrual endometrium, to animal experiments in which a forced increase in retrograde shedding increases the chance of devel- oping endometriosis [22]. It has been pointed out that menstrual re- flux, while a pre-condition for its occur- rence, is not per se sufficient to cause endometriosis: indeed, retrograde men- struation seems to occur in the vast ma- jority of women [24], whereas only a mi- nority of them develop the disease. One of the proposed explanations for this dis- crepancy is that natural immunity is al- tered in women with endometriosis; this decrease in a vital defence mechanism can cause an impairment of the physio- logic clearing ability of the peritoneum to remove endometrial fragments shed in retrograde menstruation [25, 26]. More recently, it has been found that nat- urally-occurring endometrial stem cells (ESCs) play a role in the cyclic regenera- tion of the endometrium [27]. These ESCs can also have an important role in the pathogenesis of endometriosis, since they have been found in menstrual blood [28]. In summary, whereas “there is virtually no other scientific evidence supporting alternate mechanisms of development of endometriosis” [29], there are still many questions that require an answer before Sampson’s theory can be fully accepted. The Induction (or Coelomic Metaplasia) Theory The oldest theory, dating back more than a century, to explain “epithelial invasions of peritoneal organs” involved a mecha- nism called “coelomic metaplasia”, namely the transformation of peritoneal mesothelial tissue into epithelial glands and stroma. However, the endometrial nature of these epithelial nests was not initially recognised [30] and, as a conse- quence of the work of Cullen [31], the metaplasia theory was all but abandoned until the nineteen fifties when it was res- urrected by Levander and Normann [32] and, a decade later by Merrill [33]. Ac- cording to this hypothesis, endometriosis may develop through a series of meta- plasic changes induced by the release of cellular factors from degenerating men- strual endometrium. In 1999, Ohtake et al [34] developed an in vitro experimental model for ovarian endometriosis employing a three-dimen- sional culture of human ovarian surface epithelial cells in collagen gel. Using this system, they obtained evidence that when both ovarian surface epithelium and ovarian stromal cells are co-cultured with oestradiol, endometrial-like nests Pathogenesis of Early-Onset Endometriosis 229J Reproduktionsmed Endokrinol_Online 2015; 12 (4) can develop through a process of meta- plasia. In these co-culture experiments ovarian surface epithelial and endometri- al stromal cells formed an epithelial structure with lumen, surrounded by stromal cells. Immunoreactivity for cyto- keratin and epithelial membrane antigen was detected in the glandular cells and cilia were identified on the cell surface by electron microscopy. Importantly, none of these structures were detected in the absence of oestradiol. While in vitro models support the induc- tion theory, direct evidence of the forma- tion of endometrial cells and stroma as a consequence of a metaplastic process is as yet lacking [22]. The In-situ Development Theory This hypothesis involves the growth of endometrial cells and stroma from multi- potent cells and embryonic remnants and was first presented by Ferguson et al who proposed that the peritoneal lining con- tains undifferentiated cells that can dif- ferentiate into endometrial cells under certain circumstances [35]. It has been invoked to explain cases of peritoneal endometriosis occurring be- fore menarche, in women who have nev- er menstruated, and in postmenopausal women. It has also been invoked to ex- plain extra-peritoneal cases, such as the lesions found in right-sided thoracic or- gans and in castrated men treated with oestrogens [36]. The theoretical basis of this hypothesis has been put forward by Fujii [37] who believes that a shared em- bryologic origin exists for coelomic epi- thelium-related tissues and Müllerian- derived epithelia of the adult. Thus, tis- sues derived from the coelomic epithelial and mesenchymal cells have the poten- tial to differentiate into Müllerian-type epithelium and stroma and this mecha- nism can be involved in the pathogenesis of endometriosis. New Theories The discovery that stem/progenitor cells from bone marrow can differentiate into endometrial cells suggests a novel path- way for the development of ectopic en- dometriotic implants. In a remarkable experiment, Taylor [38] obtained proof that endometrial cells can be derived from bone marrow cells, studying female allogenic bone marrow transplant recipi- ents receiving a graft under conditions allowing identification of the donated cells. This investigation demonstrated the presence of donor-derived endome- trial cells in endometrial biopsies of the recipients, suggesting that bone marrow- derived cells can differentiate into hu- man uterine endometrium.  Early-Onset Endometriosis Initially, endometriosis was considered a disease of adult women; however, taking a life cycle’s approach [39], it became clear that its presence had been described in foetuses in the posterior pelvic cavity [40], in girls before menarche [41], and during adolescence on the pelvic organs, including the ovaries [42, 43]. It seems logical that this intraperitoneal variant in young adolescents possessing in a majority of instances characteristic subtle superficial lesions with strong neo-angiogenesis, but also manifesting it with ovarian endometriomas, may have a pathogenesis that differs from cyclic retro grade menstruation. For this reason, we became interested in the pathogene- sis of this early form and decided to in- vestigate whether they may draw their origin from a totally neglected, but well proven endometrial bleeding, that occur- ring at birth in some neonates. To our surprise, over the last 30 years, we found only one report dealing with Neonatal Uterine Bleeding (NUB) pub- lished in a Yugoslavian Journal and not mentioned in any of the most widely consulted data bases [44]. By contrast, earlier publications exist on foetal and neonatal endometrium. Specifically, in the nineteen seventies French and Ger- man investigators described NUB in great detail [45–49]. Features of neonatal endometrium were carefully detailed some sixty years ago by two Harvard pathologists [50] who described the different features of neona- tal endometrium at birth as an indifferent or proliferative phase in some 2/3 of the cases. They recorded secretory activity and decidual changes in 27% and 5% of cases, respectively. Changes of the type observed at menstruation in adults were observed in 5 out of a total of 169 new- born infants, all of whom had died within 3 days after birth. Observed features in the five babies included the presence of clotted blood in the endometrial cavity; in the coagulum, sloughed endometrial structures were occasionally identifiable. The development of the endometrium during foetal life was carefully investi- gated more than 40 years ago by Huber et al [51] who documented that no glan- dular development occurs before the 20 th week, whereas signs of secretory activity can be observed in some foetuses begin- ning around the 34 th week. After birth the endometrium starts a process of regres- sion and at one week becomes quiescent. There is now unequivocal evidence that the neonatal endometrium can mount a decidual response in 5% of the neonates, a prerequisite for menstrual shedding. It is also established that overt vaginal bleeding occurs in 3–5% of the neonates and that in an unspecified larger number of new-born bleeding is occult. Regurgi- tation of sloughed endometrial frag- ments into the peritoneal cavity is likely promoted in the neonate by the thick en- docervical mucus in the relatively long cervical canal [52]. At this stage we outlined a theory to ex- plain early-onset endometriosis based on the possibility that in some foetuses and neonates endometrial cells and stroma may be retrogradely disseminated in the pelvis around the time of birth, thanks to the presence of uterine bleeding, either visible or occult [53]. This preliminary communication was followed by a full report detailing the new theory [54] and by a further article in which we discussed the possibility that menstrual debris pres- ent in NUB may contain endometrial stem cells. These neonatal ESCs may in turn be responsible, through a variety of mechanisms, for early onset endometrio- sis [55]. Today there is evidence that ESCs have the ability of establishing endometriotic implants [56] and several experiments support the hypothesis of their involve- ment in the development of the disease [57]. Following this line of thinking, we hypothesised that ESCs are shed into the pelvic cavity in concomitance with NUB. We further postulated that during the neonatal and pre-pubertal period ESCs can survive in the pelvic cavity even in the absence of circulating oestro- gens, thanks to the support of niche cells, also shed during neonatal uterine bleed- ing. Then, at the time of thelarche, under Pathogenesis of Early-Onset Endometriosis 230 J Reproduktionsmed Endokrinol_Online 2015; 12 (4) the influence of rising oestrogen levels, ESCs can proliferate and – in specific cases – establish nests of ectopic endo- metrial cells and stroma [55]. In support of our theory, two populations of ESCs have been recently identified: epithelial and mesenchymal progenitor cells (eEPCs and eMSCs). Both show a high proliferative potential, are capable of undergoing self-renewal in vitro and are capable of differentiating into mature progeny and of reconstituting tissue in vivo [58–60]. There is evidence that eMSCs from endometriotic lesions show greater invasiveness and migration abili- ty, as well as the capability to stimulate neo-angiogenesis compared to those in eutopic tissue [61]. These properties in turn may promote ESCs survival and the ability to quickly implant in the peritone- al/ pelvic cavity [62], where they can lay dormant for years [63]. Attractive as it may sound, before the new theory can be accepted it will re- quire clinical and experimental confir- mation. To this aim, we have suggested several lines of investigations [64].  Conclusions If proven true, the new hypothesis will have practical consequences also outside its possible role in early-onset endome- triosis. NUB occurs rarely in pre-term babies, increases in those at term and is frequent in post-mature infants. If a tem- poral relationship could be established between endometrial maturation and NUB, its occurrence might be taken as a reflection of the maturity of progester- one response in the endometrium. Pre- eclampsia, particularly if severe, low for gestational age birth weight, and feto- maternal blood incompatibility seem to represent factors increasing the frequen- cy of NUB [47]. For this reason, a series of new feto-maternal markers can be en- visaged to evaluate the risk of endome- triosis in adolescents and young women [65]. Finally, it has been shown that the occur- rence of major obstetric syndromes can be caused by impaired placental bed spi- ral artery remodelling [66]; these are prevalent in teenage pregnancies and in- clude pre-eclampsia, foetal growth re- striction and spontaneous preterm labour [67]. It can be argued that, if the partial progesterone resistance observed in new- born foetuses and babies can persist into adolescent years, this phenomenon may impair physiological deep placentation in case of pregnancy [66]. Thus, under- standing the mechanisms of functional maturation of the uterus during the early reproductive years may yield novel in- sights into the major obstetric syndromes [68].  Conflict of Interest All authors declare no conflict of interest. References: 1. Benagiano G, Brosens I, Lippi D. The history of endometriosis. Gynecol Obstet Invest 2014; 78: 1–9. 2. Emge L. The elusive adenomyosis of the uterus. Am J Obstet Gynecol 1962; 83: 1541–63. 3. Bird CC, McElin TW, Manalo-Estrella P. The elusive adenomy- osis of the uterus. Am J Obstet Gynecol 1972; 112: 583–93. 3. Rokitansky C. Über Uterusdrüsen-Neubildung in Uterus- und Ovarial-Sarcomen. [On the neoplasm of uterus glands on uterine and ovarian sarcomas]. Zeitschr Gesellschaft der Aerzte in Wien 1860; 16: 577–81. 4. von Recklinghausen F. Die Adenomyomata und Cystadenoma- ta der Uterus und Tubenwandung: Ihre Abkunft von Resten des Wolffi schen Körpers [The adenomyomas and cystadenomas of the uterus and tube wall: their origin from remnants of the Wolffi an body]. August Hirschwald Verlag, Berlin, 1896. 5. Cullen TS. Adenomyoma of the Uterus. WB Saunders, Phila- del phia, 1908. 6. Lockyer C. Fibroids and Allied Tumours (Myoma and Adeno- myoma). MacMillan, London, 1918. 7. Russel WW. Aberrant portions of the Müllerian duct found in an ovary. Johns Hopkins Hospital Bull 1899; 10: 8–10. 8. Sampson JA. Perforating hemorrhagic (chocolate) cysts of the ovary. Arch Surg 1921; 3: 245–323. 9. Sampson JA. The life history of ovarian hematomas (hemor- rhagic cysts) of endometrial (Müllerian) type. Arch Surg 1922; 5: 217–80. 10. Sampson JA. Peritoneal endometriosis due to the menstrual dissemination of endometrial tissue into the peritoneal cavity. Am J Obstet Gynecol 1927; 14: 422–69. 11. Halban J. Hysteroadenosis metastatica. Die lymphogene Genese der sog. Adenofi bromatosis heterotopica [Metastatic hysteroadenosis. The lymphatic origin of the so-called hetero- topic adenofi bromatosis]. Archiv Gynäkol 1925; 124: 457–82. 12. Hughesdon PE. The structure of endometrial cysts of the ovary. J Obstet Gynaecol Br Emp 1957; 44: 481–7. 13. Frankl O. Adenomyosis uteri. Am J Obstet Gynecol 1925; 10: 680–4. 14. Nisolle M, Donnez J. Peritoneal endometriosis, ovarian en- dometriosis, and adenomyotic nodules of the rectovaginal sep- tum are three different entities. Fertil Steril 1997; 68: 585–96. 15. Simpson JL, Elias S, Malinak LR, Buttram VC Jr. Heritable aspects of endometriosis. I. Genetic studies. Am J Obstet Gynecol 1980; 137: 327–31. 16. Malinak LR, Buttram VC Jr, Elias S, Simpson JL. Heritage aspects of endometriosis. II. Clinical characteristics of familial endometriosis. Am J Obstet Gynecol 1980; 137: 332–7. 17. Brosens I, Brosens JJ, Benagiano G. The eutopic endometri- um in endometriosis: are the changes of clinical signifi cance? Reprod Biomed Online 2012; 24: 496–502. 18. Benagiano G, Brosens I, Habiba M. Structural and molecular features of the endo-myometrium in endometriosis and adeno- myosis. Hum Reprod Update 2014; 20: 386–402. 19. Macer ML, Taylor HS. Endometriosis and infertility. A re- view of the pathogenesis and treatment of endometriosis-asso- ciated infertility. Obstet Gynecol Clinics North America 2012; 39: 535–49. 20. Burney RO, Giudice LC. Pathogenesis and pathophysiology of endometriosis. Fertil Steril 2012; 98: 511–9. 21. Nap AW, Groothuis PG, Demir AY, Evers JL, Dunselman GA. Pathogenesis of endometriosis. Best Pract Res Clin Obstet Gynaecol 2004; 18: 233–44. 22. Sampson JA. The development of the implantation theory for the origin of peritoneal endometriosis. Am J Obstet Gynecol 1940; 40: 549–57. 23. Halme J, Hammond MG, Hulka JF, Raj SG, Talbert LM. Retro- grade menstruation in healthy women and in patients with en- dometriosis. Obstet Gynecol 1984; 64: I51–I54. 24. Steele RW, Dmowski WP, Marmer DJ. Immunologic aspects of human endometriosis. Am J Reprod Immunol 1984; 6: 33–6. 25. Braun DP, Dmowski WP. Endometriosis: abnormal endome- trium and dysfunctional immune response. Curr Opin Obstet Gynecol 1998; 10: 365–9. 26. Chan RW, Schwab KE, Gargett CE. Clonogenicity of human endometrial epithelial and stromal cells. Biol Reprod 2004; 70: 1738–50. 27. Gargett CE, Masuda H, Schwab KE, Tan C, Weston GC. Retrograde menstruation of endometrial stem/progenitor cells in women with endometriosis. 12 th World Congress on Endo- metriosis, Sao Paolo, Brazil, April 30th–May 3 rd, 2014; M3-2.22. 28. Haney AF. Etiology and histogenesis of endometriosis. Prog Clin Biol Res 1990; 323: 1–14. 29. Iwanoff NS. Drüsiges cystenhaltiges uterusfi bromyom com- plicirt durch sarcom und carcinom. (Adenofi bromyoma cysticum sarcomatodes carcinomatosum) [Fibromyoma of the uterus con- taining cystic glands complicated by sarcoma and carcinoma]. Monatsch Geburtshilfe Gynakol 1898; 7: 295–300. 30. Cullen TS. The distribution of adenomyomata containing uterine mucosa. Arch Surg 1920; 1: 215–83. 31. Levander G, Normann P The pathogenesis of endometriosis. An experimental study. Acta Obstet Gynecol Scandin 1955; 34: 366–98. 32. Merrill JA. Endometrial induction of endomecriosis across millipore fi lters. Am J Obstet Gynecol 1966; 94: 780–9. 33. Ohtake H, Katabuchi H, Matsuura K, Okamura H. A novel in vitro experimental model for ovarian endometriosis: the three- dimensional culture of human ovarian surface epithelial cells in collagen gels. Fertil Steril 1999; 71: 50–5. 34. Ferguson BR, Bennington JL, Haber SL. Histochemistry of mucosubstances and histology of mixed mullerian pelvic lymph node glandular inclusions. Evidence for histogenesis by mulleri- an metaplasia of coelomic epithelium. Obstet Gynecol 1969; 33: 617–25. 35. Suginami H. A reappraisal of the coelomic mecaplasia theo- ry by reviewing endometriosis occurring in unusual sites and in- stances. Am J Obstet Gynecol 1991; I65: 214–8. 36. Fujii S. Secondary mullerian system and endometriosis. Am J Obstet Gynecol 1991; 165: 219–25. 37. Taylor HS. Endometrial cells derived from donor stem cells in bone marrow transplant recipients. JAMA 2004; 292: 81–5. 38. Brosens I, Puttemans P, Benagiano G. Endometriosis: a life cycle approach? Am J Obstet Gynecol 2013; 209: 307–16. 39. Signorile PG, Baldi F, Bussani R, Viceconte R, Bulzomi P, et al. Embryologic origin of endometriosis: analysis of 101 human female fetuses. J Cell Physiol 2012; 227: 1653–6. 40. Marsh EE, Laufer MR. Endometriosis in premenarcheal girls who do not have an associated obstructive anomaly. Fertil Steril 2005; 83: 758–60. 41. Yang YP, Wang Y, Jie Yang JY, Wang S, Lang JH. Adolescent endometriosis in China: a retrospective analysis of 63 cases. J Pediatr Adolesc Gynecol 2012; 25: 295–9. 42. Brosens I, Gordts S, Benagiano G. Endometriosis in adoles- cents is a hidden, progressive and severe disease that deserves attention, not just compassion. Human Reproduction 2013; 28: 2026–31. 43. Beric BM, Prodanovic Z, Mitrovic M, Curcic O. Uterino krvav- ljenje u novorodene dece [Uterine hemorrhage in newborn]. Jugoslav Ginekol Perinatol 1985; 25: 89–98. 44. Kaiser R, Grässel G. Frequenz und Starke der uterinen Neu- geborenen-blutung [Incidence and intensity of uterine bleeding in the neonate]. Geburtsh Frauenheilk 1974; 34: 644–8. 45. Kaiser R, Grässel G, Berger Lang R. Über die uterine Blutung neugeborener Mädchen [Uterine bleeding in newborn girls]. Dtsch Med Wochenschr 1974; 99: 1769–71. 46. Levy JM, Rosenthal R, Dellenbach P, Pequenot JP. Crise gé- nitale du nouveau-né. Répercussion de certains facteurs mater- nels ou gravidiques sur la fréquence des métrorragies néona- tales. [Genital crisis in the newborn. repercussion of certain ma- Pathogenesis of Early-Onset Endometriosis 231J Reproduktionsmed Endokrinol_Online 2015; 12 (4) ternal or pregnancy factors on the frequency of neonatal metror- rhagia]. Arch Fr Pediatr 1964; 21: 819–27. 47. Kaiser R, Grässel G. Frequenz und Starke der uterinen Neu- geborenen-blutung [Incidence and intensity of uterine bleeding in the neonate]. Geburtshilfe Frauenheilk 1974; 34: 644–8. 48. Huber A. Häufi gkeit der physiologischen vaginalen Neuge- borenenblutung [Frequency of physiological vaginal hemorrhage in the newborn]. Zentralbl Gynäkol 1976; 98: 1017–20. 49. Ober WB, Bernstein J. Observations on the endometrium and ovary in the newborn. Pediatrics 1955; 16: 445–60. 50. Huber A, Michael S, Feik K. Funktionelle Veränderungen am fetalen und kindlichen Endometrium [Functional changes in the fetal and infantile endometrium]. Arch Gynäk 1971; 211: 583– 94. 51. Fluhmann C. The developmental anatomy of the cervix uteri. Obstet Gynecol 1960; 15: 62–9. 52. Brosens I, Benagiano G. Is neonatal uterine bleeding involved in the pathogenesis of endometriosis as a source of stem cells? Fertil Steril 2013; 100: 622–3. 53. Brosens I, Brosens J, Benagiano G. Neonatal uterine bleed- ing as antecedent of pelvic endometriosis. Hum Reprod 2013; 28: 2893–7. 54. Gargett E, Schwab KE, Puttemans P, Brosens JJ, Benagiano G, Brosens I. Potential role of endometrial stem/progenitor cells in the pathogenesis of early-onset endometriosis. Mol Hum Reprod 2014; 20: 591–8. 55. Seli E, Berkkanoglu M, Arici A. Pathogenesis of endometrio- sis. Obstet Gynecol Clinics North Am 2003; 30: 41–61. 56. Sasson IE, Taylor HS. Stem cells and the pathogenesis of endometriosis. Ann N Y Acad Sci 2008; 1127: 106–15. 57. Masuda H, Maruyama T, Hiratsu E, Yamane J, Iwanami A, et al. Noninvasive and real-time assessment of reconstructed functional human endometrium in NOD/SCID/gamma c(null) im- muno-defi cient mice. Proc Natl Acad Sci USA 2007; 104: 1925– 30. 58. Gargett CE, Schwab KE, Zillwood RM, Nguyen HP, Wu D. Isolation and culture of epithelial progenitors and mesenchymal stem cells from human endometrium. Biol Reprod 2009; 80: 1136–45. 59. Chan RW, Ng EH, Yeung WS. Identifi cation of cells with col- ony-forming activity, self-renewal capacity, and multipotency in ovarian endometriosis. Am J Pathol 2011; 178: 2832–44. 60. Kao AP, Wang KH, Chang CC, Lee JN, Long CY, et al. Com- parative study of human eutopic and ectopic endometrial mes- enchymal stem cells and the development of an in vivo endome- triotic invasion model. Fertil Steril 2011; 95: 1308–15. 61. Witz CA, Thomas MR, Montoya-Rodriguez IA, Nair AS, Centonze VE, Schenken RS. Short-term culture of peritoneum explants confi rms attachment of endometrium to intact perito- neal mesothelium. Fertil Steril 2001; 75: 385–90. 62. Rajkumar K, Schott PW, Simpson CW. The rat as an animal model for endometriosis to examine recurrence of ectopic endo- metrial tissue after regression. Fertil Steril 1990; 53: 921–5. 63. Brosens I, Curcic A, Vejnovic T, Gargett CE, Brosens JJ, Benagiano G. The perinatal origins of major reproductive disor- ders in the adolescent. Placenta 2015; 36: 341–4. 64. Brosens I, Curcic A, Vejnovic T, Gordts S, Gargett C, et al. Neonatal uterine bleeding and risk of endometriosis: a call for registration. J Ped Adolesc Gynecol 2015 [E-pub ahead of print]. 65. Brosens I, Pijnenborg R, Vercruysse L, Romero R. The “Great Obstetrical Syndromes” are associated with disorders of deep placentation. Am J Obstet Gynecol 2011; 204: 193–201. 66. Chibber R, Fouda M, Al-Hijji J, Al-Dossary M, Sadeq EH, et al. Adverse pregnancy outcome among teenagers: A reality? J Obstet Gynaecol 2014; 34297–300. 67. Brosens I, Benagiano G, Brosens JJ. The potential perinatal origin of placentation disorders in the young primigravida. Am J Obstet Gynecol 2015; 212: 580–5. 68. Brosens I, Benagiano G. The endometrium from the neonate to the adolescent. J Mat Fet Neonat Health 2015 [E-pub ahead of print]. Haftungsausschluss Die in unseren Webseiten publizierten Informationen richten sich ausschließlich an geprüfte und autorisierte medizinische Berufsgruppen und entbinden nicht von der ärztlichen Sorg- faltspflicht sowie von einer ausführlichen Patientenaufklärung über therapeutische Optionen und deren Wirkungen bzw. Nebenwirkungen. 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