Transplantation in reproductive medicine: previous experience, present knowledge and future prospects.
The use of transplantation in reproductive medicine has been considered by physicians and scientists alike for many years. Despite being side-tracked into futile pursuits of rejuvenation in the early days, the possibility of usefulness remains, particularly for preserving fertility in patients undergoing ablative chemo- or radiotherapy. These aims have been enhanced by advances in tissue cryopreservation. When isolated primordial follicles are transferred in the mouse, or ovarian tissue slices are grafted into sheep, it is possible to obtain follicular survival with subsequent maturation and oestrogen secretion and even restore fertility to sterilized hosts. For preservation of fertility, autografts avoid both the immunological problems of allografts and the ethical dilemmas when using donor tissue. In the male, the concept of spermatogonial cell transfer after isolation and frozen storage of cells recovered from a testicular biopsy is most attractive, since it may provide another option for rescuing fertility in cancer patients, and provide a much needed one in children. Recent results demonstrate that gonocytes from immature mice injected into the tubules of sterilized hosts restore spermatogenesis and produce fertile spermatozoa. Furthermore, the gonocytes can be stored frozen prior to transfer and still produce fertile tubules. This review presents a broad history of transplantation in the male and female genital tracts as well as attempts to anticipate possible future developments.