The field of reproductive medicine is evolving rapidly. We are living in an era in which what was seemingly impossible a decade ago is being made possible, and century-old dogmas are being challenged. Thanks to new cryopreservation technologies, infertility and premature ovarian failure, especially when induced by medical treatments, are no longer unavoidable consequences. Whereas success with oocyte cryopreservation is gradually approaching acceptable levels for use in patients who face the risk of ovarian failure due to medical treatments or to create “egg banks” for oocyte donation, ovarian tissue cryopreservation and transplantation promise to be a way to reverse menopause and restore fertility. Yet, the recently proposed possibility of the presence of germ stem cells in human bone marrow is even more intriguing. Whereas bone marrow and peripheral blood transplants result in repopulation of chemotherapy-treated ovaries with primordial follicles in rodents, germ stem cell markers are already shown in human bone marrow and peripheral blood. According to this theory, the ovaries provide signals to the germ stem cells residing in the bone marrow and recruit new follicles via the bloodstream “on demand.” Although shocking and contrary to the preexisting dogma that the ovarian reserve is predetermined before birth, this hypothesis is not without supporting evidence in humans and nonhuman primates, as illustrated by the following case study.

Endometriosis is classically defined as the presence of endometrial glands and stroma in ectopic locations. Affecting from 6% to 10% of reproductive-aged women, endometriosis may result in dysmenorrhea, dyspareunia, chronic pelvic pain, and/or subfertility. The prevalence of this condition in women experiencing pain, infertility, or both is as high as 50%. Endometriosis is a debilitating condition, posing quality-of-life issues for the individual patient. The disorder represents a major cause of gynecologic hospitalization in the United States, estimated to have exceeded $3 billion in inpatient health care costs in 2004 alone. The significant individual and public health concerns associated with endometriosis underscore the importance of understanding its pathogenesis. The first recorded description of pathology consistent with endometriosis was provided by Shroen in 1690. Despite the passage of time and extensive investigation, the exact pathogenesis of this enigmatic disorder remains unknown.

THEORIES REGARDING PATHOGENESIS

Numerous theories detailing the development of endometriosis have been described. For purposes of review, these theories can generally be classified into those that propose that implants arise from tissues other than the endometrium and those that propose that implants arise from uterine endometrium (Table 10.1.1).

Nonendometrial Origin

Metaplasia of coelomic epithelium represents a distinct pathogenic mechanism for the establishment of endometriotic implants.