The impact of heterotopic ovarian tissue transplantation with varied volumes on reproductive endocrine function in oophorectomized rats.

ABSTRACT

BACKGROUND: This study aimed to investigate the effects of different volumes of ovarian tissue transplantation on the reproductive endocrine function of rats after oophorectomy. METHODS: Female rats were selected to establish a castration model and then underwent different volumes of ovarian tissue transplantation. Group I served as the sham operation group. The transplantation group was divided into five subgroups based on the calculated ratio of ovarian weight to body weight in normal female rats, δ = (2.52 ± 0.17) ×10-4 Group II transplanted ovarian volume was δ; Group III 0.75δ; Group IV 0.5δ; Group V 0.25δ; Group VI without ovarian transplantation. The post-transplant oestrous cycle recovery was observed, and blood samples were collected every 2 weeks to measure serum hormone levels. Histological evaluation was performed at the end of the observation period. RESULTS: Rats in Group V exhibited disrupted oestrous cycles after transplantation, which were significantly longer than those in Group I. Rats in Groups II, III, and IV showed no cyclic changes. At 6 weeks post-transplantation, rats in Group V had lower E2 and AMH levels and higher FSH levels compared to Group I. The uterine wet weight and the number of normal follicles in Group V were significantly lower than those in Group I, but the number of atretic follicles was higher than in Group I. CONCLUSION: The larger ovarian tissue transplantation resulted in a faster recovery with a higher survival rate of the uterus and normal follicles, compared to smaller ovarian tissue transplantation.

With advancements in science and technology, ovarian transplantation techniques have become increasingly mature. However, there are still many questions that need to be addressed. For instance, the large size of the transplanted ovarian tissues may cause over-recruitment of the primordial follicles. When the transplanted ovarian tissue is too small, it can only exert limited functionality and may not meet the patient's needs. This study aimed to investigate the effects of different volumes of ovarian tissue transplantation on the reproductive endocrine function in rats after oophorectomy, and to provide a theoretical basis for determining the minimum effective volume of heterotopic ovarian tissue transplantation.