Abstract
PURPOSE: Ovulation induction and oocyte retrieval were performed in a lowland gorilla in an attempt to propagate and potentially cryopreserve embryos from an infertile animal and to advance techniques to help preserve this endangered species. RESULTS: Following 34 days of leuprolide acetate suppression, human menopausal gonadotropins were administered for 14-days in a 32-year-old wild-born lowland gorilla. Ten oocytes were retrieved by transrectal ultrasound-guided aspiration. Other approaches to oocyte recovery were not feasible in this case. A serum estradiol concentration of 4700 pg/ml at the time of human chorionic gonadotropin administration did not induce ovarian hyperstimulation. Mature oocytes were recovered from follicles measuring 14 to 24 mm in diameter, with a corresponding average serum estradiol concentration of approximately 300 pg/ml for each mature follicle. Cryopreservation of a gorilla embryo was effected from cryopreserved gorilla spermatozoa. CONCLUSIONS: Parameters for monitoring ovulation induction in the gorilla appear to be similar to those for humans. The results indicate that the use of a gonadotropin releasing hormone agonist and higher doses of gonadotropins than previously used in gorillas appear to improve oocyte recovery.