w' FERTILITY AND STERILITY Copyright c 1991 The American Fertility Society Vol. 56, No.6, December 1991 Printed on acid-free paper in U.S.A. Penetration of zona-free hamster oocytes by ejaculated cryopreserved gorilla spermatozoa Hovey Lambert, Ph.D. * Scott Citino, D.V.M.t:!: Ineabelle Collazo, B.S.* Rajasingam S. Jeyendran, D.V.M., Ph.D.§1I Mount Sinai Medical Center, Miami Beach, Miami Metrozoo, Miami, Florida, and Northwestern University Medical School, Chicago, Illinois The development of in vitro fertilization (IVF) procedures in human and other animals has opened a new approach to propagation of captive lowland gorillas. Although there is virtually no information available for gorillas, by using the knowledge and experience gained from human IVF procedures, in- vestigators have obtained successful fertilization in gorillas using cryopreserved epididymal sper- matozoa 1 ,2 or using ejaculated spermatozoa. 3 This approach, although successful, is not practical be- cause of limited availability of epididymal or ejac- ulated gorilla sperm. To date, no reports are avail- able on the use of cryopreserved ejaculated gorilla spermatozoa for an IVF program. Previous studies have indicated that sperm pen- etration into zona-free hamster oocytes may provide information about the ability of spermatozoa from a heterologous species to undergo capacitation and acrosome reaction. 4 Because these sperm alterations are a prerequisite for fertilization, the sperm pene- tration assay (SPA) can be used to assist in the de- velopment of a sperm-processing procedure to ca- pacitate gorilla spermatozoa. Such a procedure will Received April 15, 1991; revised August 19, 1991. * Reproductive Biology Research Foundation Inc., Mount Sinai Medical Center. t Miami Metrozoo. * Present address: Smithsonian Institution, Washington, D.C. 20008. § Department of Obstetrics and Gynecology, Northwestern University Medical School. II Reprint requests: Rajasingam S. Jeyendran, D.V.M., Ph.D., 333 East Superior, Suite 1506, Chicago, Illinois 60611. Vol. 56, No.6, December 1991 facilitate gorilla IVF programs, especially if ejacu- lated cryopreserved spermatozoa could be used. This study was performed to evaluate the ability of ejac- ulated cryopreserved gorilla sperm to penetrate zona-free hamster oocytes. MATERIALS AND METHODS Semen Collection Two healthy male lowland gorillas housed at Miami Metrozoo were placed in dorsal recumbency after sedation with 500 mg of intramuscular Telazol by blowdart and maintained with ketamine HCI as needed through an intravenous port (Ketaset, Bris- tol Laboratories, Syracuse, NY). Semen was col- lected after electroejaculation with a 2.5 to 3.0-cm- diameter rectal probe placed with the electrodes positioned vertically in the pelvic rectum. The an- imal underwent three series of 10 stimulations, each with a 5 to 10-minute rest between series. Stimu- lation was increased by 1 volt with each series, and the probe position was adjusted within the rectum to obtain maximal erection and ejaculation. The electroejaculations were performed once a month on each animal. Of the six attempts at electroejacula- tion, four (2 from each animal) yielded semen that could be analyzed and cryopreserved. Sperm Processing The sperm concentration and motility were de- termined using a Makler Chamber (T.S. Scientific, Perkasie, PA). To 0.25 mL of ejaCUlate in 1.5-mL Lambert et aI. Communications-in-brief 1201