STRATEGIES FOR OVULATION INDUCTION AND OOCYTE RETRIEVAL IN THE LOWLAND GORILLA

Purpose: Ovulation induction and oocyte retrieval were performed in a lowland gorilla in an attempt to propagate and potentially cryopreserv e embryos from an infertile animal and to advance techniques to help p reserve this endangered species. Results: Following 34 days of leuprol ide acetate suppression, human menopausal gonadotropins were administe red for 14-days in a 32-year-old wild-born lowland gorilla. Ten oocyte s were retrieved by transrectal ultrasound-guided aspiration. Other ap proaches to oocyte recovery were not feasible in this case. A serum es tradiol concentration of 4700 pg/ml at the time of human chorionic gon adotropin administration did not induce ovarian hyperstimulation. Matu re oocytes were recovered from follicles measuring 14 to 24 mm in diam eter with a corresponding average serum estradiol concentration of app roximately 300 pg/ml for each mature follicle. Cryopreservation of a g orilla embryo was effected from cryopreserved gorilla spermatozoa. Con clusions: Parameters for monitoring ovulation induction in the gorilla appear to be similar to those for humans. The results indicate that t he use of a gonadotropin releasing hormone agonist and higher doses of gonadotropins than previously used in gorillas appear to improve oocy te recovery.