On-site maturation and fertilization of African lion (Panthera leo) oocytes

African lions reproduce well in zoos leading to the fact that occasionally ovaries and testis are available for in vitro experiments. We previously performed in vitro maturation (IVM) and fertilization (IVF) of lion oocytes in our laboratory and were able to produce advanced embryos after intracytoplasmic sperm injection (ICSI) with cryopreserved sperm [1]. Here we examined whether our methods can also be performed on-site without a specialized IVF laboratory in order to minimize transport ways and risks. Thus, on-site means neither in vivo nor a fully field-tested cascade of IVF techniques. Rather it is a first out-of-the-lab step towards an implementation of IVF under field-like conditions. Oocytes of five lionesses (one to 13 years old) were obtained after euthanasia for population management in two safari parks and immediately processed on site. Oocytes (n = 216) were cultured for IVM in Quinn’s Advantage Protein Plus™ Blastocyst Medium supplemented with 0.2 IU /mL human luteinizing hormone (LH) and 0.5 IU /mL human pituitary follicle-stimulating hormone (FSH) in a transportable incubator for 26-32 hours. Conditions were set to 39ºC, 5% CO2 and humidified air atmosphere. Afterwards, the oocytes were fertilized with frozen-thawed epididymal sperm of three different males and fresh epididymal sperm of one male. One hundred and twenty-two (56.5%) oocytes matured, and 32 zygotes (26.2%) cleaved after in vitro fertilization under the same on-site conditions. Vitrification was finally performed under laboratory conditions with 16 embryos, most of them at an early cleavage stage of 2-8 cells. These embryos are still frozen for potential transfer experiments. The rest of the embryos was cultured for up to seven days. One blastocyst and three morulae developed, although most of the embryos arrested at an early cleavage stage, which was also observed in former experiments under optimal laboratory conditions. These results demonstrated not only the possibility of “on site” IVF of African lion oocytes but also allowed vitrification of early stage lion embryos for the first time. In the future, the complete IVF procedure from oocyte retrieval to embryo transfer in African lions could become conceivable under “on site” or even field conditions. [1] Fernandez-Gonzalez L, Hribal R, Stagegaard J, et al. Production of lion (Panthera leo) blastocysts after in vitro maturation and ICSI. Theriogenology 2015;83:995-9.