Transplantation of the Uterus in the Male Rat

Abstract

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.

FIGURE 1.

The procedure of left inguinal uterus transplantation (UTx) in castrated male rats. A, Donor preparation: The left common iliac artery (LCIA) and left common iliac vein (LCIV) were used as the donor-anastomosed vessels. The left superior vesical artery and vein derived from the left common illac artery and vein supplied the left uterus with bloods. B, The left uterus, ovary, and upper vagina after perfusion. C, Recipient preparation: The left femoral artery (LFA) and left femoral vein (LFV) were used as the anastomosis vessels of receptors. D, Recanalization after vascular anastomosis was completed. E, The transplanted left uterine grafts in the groin after hyperemia. F, The closed inguinal incision and vaginal ostomy. AS, anastomotic site; LO, left ovary; LU, left uterus; UV, upper vagina.

FIGURE 2.

Macroscopic appearances of the grafts on day 30 after transplantation. A, The stoma was pink in color, and the anteroposterior vaginal walls were adjacent to the skin of the groin. B, Uterus adhered to abdominal wall with a good blood supply. C, Anastomosed blood vessels showing smooth blood flow. D, Uterus and ovary surrounded by fibrous connective tissue. AS, anastomotic site; LU, left uterus; UV, upper vagina.

FIGURE 3.

Histological features of the transplanted uteri. A, The whole morphology of UTx1. B, The endometrium was lined by cuboidal to columnar epithelium. Mitosis (yellow arrow) and infiltrated leukocytes (black arrows) were present in the transplanted uterus (UTx1). C, Uterine endometrial gland dilation and mitotic activity (yellow arrow, UTx1) were observed in the glandular cells. D, Image from the uterus of UTx5. E, The cells lining the endometrial lumen presented notable necrosis and infiltrated with lot of neutrophils (black arrows, UTx5). F, Dilated glands were examined (UTx5). G, The histological appearance of uterus of UTx4. H, Uterine endometrium lined by low columnar epithelium (UTx4). I, The endometrial gland cells showed no characteristics of mitotic activity or apoptosis (UTx4). UTx, uterus transplantation.

FIGURE 4.

Histological characteristics of the transplanted vaginas. A, The gross appearance of vagina from UTx4. B, The vagina was composed of stratum germinativum (SGerm), stratum granulosum (SG), stratum corneum (SC), and stratum mucification (SM). C, Both attached and detached cornified epithelia were examined underneath the vagina from UTx1. D, Inflammatory cells (black arrows) infiltrated in the vaginal stroma. E, In the vagina from UTx6, the stratum corneum and stratum granulosum were lost. F, Polymorphonuclear inflammatory cell (black arrow) present in the vaginal epithelium. UTx, uterus transplantation.

FIGURE 5.

Histological analysis of transplanted ovaries. A, The transplanted ovary was surrounded by fibrous tissue. Follicles of different stages were found in the transplants. The normal primordial (B, black arrow), primary (C), secondary (D), and tertiary follicles (E) can be found, respectively. Abnormal primordial (F, black arrow), primary (G), secondary (H), and tertiary follicles (I) could also be observed. Corpus luteum with different histological characteristics were found in the transplanted ovaries. Some of the cells in the corpus luteum harbored eosinophilic cytoplasm. Fibrous tissue proliferation could also be found (J and K). L, Cells with basophilic cytoplasm can be observed in the corpus luteum.

FIGURE 6.

TUNEL staining affirmed the apoptosis of granulosa cells in both normal (A–C) and transplanted ovaries (D–F). The green fluorescence indicated the apoptotic cells (A and D). The nucleus was stained with DAPI (B and E). The merged images (C and F). The median numbers of apoptotic cells in the normal ovaries and transplanted ovaries were 10 (4, 28) and 82 (7, 387), respectively. **P < 0.01.