Vitrification of Ovarian Tissue from Primates and Domestic Ruminants: An Overview Luana N. Santana, 1,2 Rob Van den Hurk, 3 Irma C. Oskam, 4 Adriel B. Brito, 1,2 Danielle C. Brito, 1,2 Sheyla F.S. Domingues, 1,2 and Regiane R. Santos 1–3 In the last decade, vitrification protocols to preserve human ovarian tissue have been regularly reported, even more often than the protocols developed for large mammals, such as ruminants and nonhuman primates. In order to facilitate the use of domestic ruminants (cows, goats, and sheep) and nonhuman primates as animal models, application of similar protocols as used for human material is performed. Next to it, the addition of indispensable or exclusion of avoidable compounds in the vitrification of human ovarian tissue should be tested in such experiments with animal models. The objective of this mini-review is to summarize the current protocols used for the vitrification of ovarian tissue and to evaluate the vitrification methods in humans, nonhuman primates, and domestic ruminants. Introduction I n 1986, Fahy suggested the use of vitrification as an al- ternative for organ cryopreservation. 1 Ten years later, the groundbreaking studies of Sugimoto et al. 2 showed the possibility of vitrifying ovarian tissue from neonatal rats. Therefore, pioneering studies from Fahy 1 and Sugimoto et al. 2 constituted the basis of the ovarian tissue vitrification research from the past 15 years. In 2002, De la Pen ˜ a and co- workers 3 reported the birth of pups after transfer of mouse embryos derived from vitrified preantral follicles (PFs). Though mice and rats are not the most appropriate models for large mammals regarding ovarian tissue cryo- preservation, such approach helped to elicit further under- standing of the preservation of female fertility. The first report of ovarian tissue vitrification in large mammals was published by Isachenko et al., 4 who performed vitrification of human ovarian tissue. More recent studies involving other large mammals, such as nonhuman primates and ruminants, have been carried out. In 2005, live births were reported after vitrification of hemi-ovaries, followed by autotransplantation in sheep. 5 Although such success has not been repeated, as yet, in other large mammals, this is a confirmation that vitrification of ovarian tissue is a very promising technique. In contrast to slow freezing, which can not be applied in whole organs, vitrification eliminates the risks of intracellular formation of hexagonal ice-crystals. 6 Furthermore, when wild mammals are found dead in the zoo or in remote areas, the ovarian tissue can be immedi- ately preserved by vitrification without the need of elec- tricity or complex equipments. In the present review, we summarize the advances and challenges involving the vit- rification of ovarian tissue from primates and domestic ruminants in order to preserve PFs. Animal Model or Direct Application? Cryopreservation of ovarian tissue is an important tool to preserve the fertility of women prior to cancer treatment onset, 7 as well as to preserve animal biodiversity. 8 In both cases, domestic ruminants (sheep, goats, and cows) and nonhuman primates can be used as animal models to de- velop and optimize cryopreservation protocols. However, based on a compilation of publications with respect to vit- rification of PFs at MEDLINE, most of the studies have been performed using human ovarian tissue. Table 1 summarizes information on the vitrification of ovaries and ovarian fragments of primates (human and nonhuman) and domestic ruminants from 2003 up to 2011. The increased interest in ovarian tissue vitrification is shown by the high percentage (45.5%, i.e., 15 from 33) of the ovarian studies that have been published in the last 2 years. From 2003 to November 2011, 51.5% of the vitrification studies with ovarian tissue were accomplished with human tissue, 1 Laboratory of Wild Animal Biology and Medicine and 2 Animal Science Post-graduation Program, Universidade Federal do Para ´, Brazil. 3 Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands. 4 Biokapital, Geno. Hamar, Norway. BIOPRESERVATION AND BIOBANKING Volume 10, Number 3, 2012 ª Mary Ann Liebert, Inc. DOI: 10.1089/bio.2011.0048 288