Inhibin and follicular development in heterotopical ovary transplants without vascular pedicle in syngeneic Lewis rats.

Objective: To evaluate the role of inhibin in elevated base levels of FSH and follicular hyperplasia in ovarian autotransplantation in rats.

Design: Experimental animal study.

Setting: Unit of Experimental Research at the Barcelona University School of Medicine.

Animal(s): Female syngeneic Lewis rats aged 16 weeks.

Intervention(s): The animals were randomized into two groups: group A, control group undergoing only laparotomy (n = 5) and group B, oophorectomized with SC autologous heterotopic transplant (n = 5). The animals were killed and their ovaries removed for histologic, morphometric, and immunohistochemical analysis at 28 days after surgery in both groups.

Main Outcome Measure(s): Serum levels of E2 and FSH were determined on day 0 (the day of surgery or baseline) and days 4, 7, 14, 21, and 28. Morphometric analysis of ovarian structure for evaluation of antral follicles and their granulosa cell area and immunohistochemistry for inhibin staining were also done.

Result(s): The endocrinological function recovered at 28 days, and the FSH levels for the transplant group were significantly higher than for the group with normoinsert ovary. Morphometric analysis showed that the mean granulosa cell area was greater in group B when compared with the control group. Immunohistochemistry revealed almost null inhibin staining of the stroma in transplanted ovarian tissue.

Conclusion(s): Tissue damage brought on by ischemia in the transplant of nonvascularized ovaries may bring about an inhibin deficit in the ovarian stroma, which might explain the increased levels of FSH. These increased levels, in turn, would be responsible for the follicular hyperplasia seen in this tissue when it recovers its function.