Transplantation of the Uterus in the Male Rat.

Background: Uterus transplantation (UTx) is one of the potential methods to cure absolute uterine factor infertility of transgender. However, this mostly comes with many technological challenges.

Methods: Left inguinal UTx was performed in 13 castrated male rats. End-to-end anastomosis of donor common iliac vessels to recipient femoral vessels was used for transsexual UTx. Sampling was performed on day 30 after transplantation. Grafts were used to analyze the histological changes. TUNEL assay was applied to stain the apoptotic cells. Immunological rejection was judged by flow cytometry.

Results: Six uteri, 4 ovaries, and 4 upper vaginas were found at day 30 posttransplantation. Similar histological changes to proestrus, estrus, and diestrus of female rats were examined in the transplanted uteri. The histological changes of transplanted vaginas showed similarity to proestrus, estrus, and metestrus of the female rats. Follicles of different stages and corpus luteum with distinct morphological appearances were also observed. The TUNEL assay revealed a higher apoptosis of granulosa cells in transplanted ovaries compared with normal ovaries.

Conclusions: A rat model of transsexual unilateral inguinal uterine transplantation in castrated rats was established, which will provide a reference for bilateral transsexual UTx in animals and genetically 46 XY individuals who wish to become real women through transsexual UTx.