Efficacy of Porcine Gonadotropins for Repeated Stimulation of Ovarian Activity for Oocyte Retrieval and In Vitro Embryo Production and Cryopreservation in Siberian Tigers (Panthera tigris altaica)1

Abstract

A comparison of the amino acid sequences demonstrated that Siberian tiger gonadotropins are more homologous with those of porcine than any other commercially available preparation. The present study measured the efficacy of repeated ovarian stimulation with purified porcine gonadotropins on the follicular, hormonal, and immunogenic responses in Siberian tigers as well as on the ability of oocytes retrieved by laparoscopic follicular aspiration to fertilize and cleave in vitro. Controlled rate and vitrification cryopreservation methods were also compared for their ability to support ongoing cleavage following thawing of presumptive 2- to 4-cell tiger embryos generated in vitro. Vitrification supported continued embryonic cleavage in vitro while controlled rate freezing did not. Stereological microscopy indicated an excellent ovarian response with the recovery of quality cumulus-oocyte complexes that apparently fertilized and cleaved in vitro. However, ultrastructural and physiological examination revealed abnormal and unnatural responses such as the failure of some cumulus-oocyte complexes to reach maturity and progestagen levels to approach normalcy. At the same time, analyses of blood for antibodies failed to detect an immune reaction to these foreign gonadotropins in an assay that tested positive for the chorionic gonadotropin-stimulated domestic cat. Together, these observations suggest that porcine gonadotropins may be effective for the ovarian stimulation of tigers but that some modifications to administration protocols are needed to produce a more natural response.

Genome Banking for Vertebrates Wildlife Conservation

“…None of the slow freezing embryos survived (0/89). From those vitrified, 46% (32/70) survived (Crichton et al, 2000;Crichton et al, 2003).…”

Wildlife Cats Reproductive Biotechnology

“…Equine Chorionic Gonadotropin (eCG) and Human Chorionic Gonadotrophin (hCG) are frequently used due to their long half-life in circulation (24-48h) and good ovarian response with a single application. Other hormones used are the porcine Follicle Stimulating Hormone (pFSH) and porcine Luteinizing Hormone (pLH), these hormones are characterized as short half-life (~ 2h) gonadotropins, therefore, they present the disadvantage of requiring multiple applications to produce a good ovarian response (Crichton et al, 2003;Dresser et al, 1988;Pope, 2000;Wildt et al, 1981).…”

“…The FSH and hCG combination was used successfully in the Indian desert leopard (Felis sylvestris ornata) (Pope et al, 1989), and the pFSH and pLH combination in tigers (Crichton et al, , 2003 jaguars (Panthera onca) , ocelots (Leopardus pardalis) and tigrinas (Leopardus tigrinus) (Paz et al, 2005. Swanson et al (1995Swanson et al ( , 1996a suggest that the repeated administration of exogenous gonadotropins, within short time intervals is a problem because it causes a reduction in the ovarian stimulation which is immunologically mediated.…”

Foreword: A perspective on the role of emerging technologies for the propagation of companion animals, non-domestic and endangered species

“…Described problems with in vitro-produced embryos include: (i) occurrence of cytogenetic and ultrastructural changes; (ii) increased abortions, perinatal loss or fetal abnormalities; and (iii) skewed sex ratio in favour of males (Loskutoff 2003;Fleming et al 2004). For example, conventional protocols for gonadotrophin stimulation, oocyte recovery and IVF in the tiger resulted in abnormal endocrine profiles and oocyte and embryo morphology (Crichton et al 2003). A better understanding of and insight into regulatory processes is essential when using ART to create optimal conditions during several critical time points in development.…”