Penetration of zona‐free hamster ova by Siberian tiger sperm

Abstract

Sperm from the electroejaculate of captive Siberian tigers (Punthem tigris ultuicu) penetrated zona pellucida-free hamster ova in vitro, evidenced by a decondensation reaction. This assay, when used in conjunction with semen analysis, may be useful in assessing the fertility potential of males of this and other related felids. Such information is an important step in developing successful long-term management strategies for captive and wild populations of this severely endangered species. Key words: sperm penetration assay, reproduction, Siberian tigers, conservation INTRODUCTIONThe zona-free hamster ovum sperm penetration assay (SPA) is the only routine diagnostic method available for evaluating human sperm function; the SPA in conjunction with sperm concentration, morphology, viability, lateral head displacement, and forward progression can be used to predict human male fertility with a high degree of confidence [Margalioth et al, 1983; Rogers et al, 1983; Aitken, 19841. The SPA has been used to evaluate sperm of several domestic species [Yanagimachi, 1972; Imai et d, 1977; Lorton and First, 19791, as well as one species of cetacean [Fleming, 19811. Although there are records of in vitro fertilization in the domestic feline [Hamner et al, 1970; Bowen, 1977; Niwa et al, 19851, the SPA has not previously been used to evaluate feline sperm. Here we report that sperm from captive Siberian tigers is capable of penetrating zona-free hamster ova and suggest how the assay might be utilized in developing long-term management strategies for both captive and free-ranging tiger populations.Received for publication December 13, 1985; accepted September 12, 1986. MATERIALS AND METHODSThe three electroejaculates used in this study were collected from tigers at the Minnesota Zoo during their 1985 breeding season [Seal et al, 19851. Within 2-3 hr after ejaculation, count and motility were evaluated, and the SPA was performed.The SPA was carried out by a modification of the method of Yanagimachi and colleagues [1976]. The tiger ejaculate was diluted 1: 1 with Biggers, Whitten, and Whittingham's medium (BWW) [Biggers et al, 19711 containing 3 mg/ml bovine serum albumin and centrifuged for 10 min at 300 x G . All but 0.5 ml of the supernatant was removed, and the pellet was resuspended in the remaining liquid, to concentrate the sperm to 50-80 x 106/ml, and incubated until use. Tiger semen samples obtained earlier and incubated for 18 hr (the incubation period used for human samples) at 37°C showed a loss of motility, dropping from 70% to 0%. Therefore, preincubation times were shortened to approximately 2 hr.Mature golden hamsters were superovulated with 40 IU pregnant mare serum gonadotropin injected IP on the morning of post-estrus when sticky, vaginal discharge is obvious, and 25 IU human chorionic gonadotropin (HCG) 55 hr later. Eighteen hours after HCG, the animals were sacrificed, and their oviducts excised. Under a dissecting microscope the cumulus masses were released by pricking the distended portion of the oviduct...

Ejaculate‐hormonal traits in the leopard cat (Felis bengalensis) and sperm function as measured by in vitro penetration of zona‐free hamster ova and zona‐intact domestic cat oocytes

“…This study provides evidence that leopard cat spermatozoa are capable of penetrating heterologous oocytes in vitro. Spermatozoa from one other species of nondomestic felid, the Siberian tiger (Panthera tigris altaica), have been shown to penetrate zona-free hamster ova (Post et al, 1987;Byers et al, 1987Byers et al, ,1989. In this species, this bioassay was effective for assessing various preincubation and coculture conditions and sperm functionality.…”