Oocyte developmental competence is improved by relatively greater circulating progesterone concentrations during preovulatory follicular growth

From reproductive technologies to genome editing in small ruminants: an embryo s journey

“…The pregnancy rate obtained with the short-term protocol associated with FTAI, and associated with natural mating or conventional artificial insemination, has been previously published in several reports in sheep and goats (Ungerfeld and Rubianes, 1999;Rubianes 2004, 2007;Fonseca et al, 2005Fonseca et al, , 2017. In addition, we have recently generated new information on large-scale FTAI programs on more than 13,000 ewes (Menchaca, 2018;IRAUy, Montevideo, Uruguay;unpublished results). In these programs, progesterone priming was administered by using intravaginal devices containing 0.3 g of progesterone (DICO, Syntex, Argentina) as described previously Santos-Neto et al, 2015a).…”

“…We have recently demonstrated in sheep the convenience of exposing the oocyte to high progesterone concentrations prior to maturation, i.e., during preovulatory follicular development (Cuadro et al, 2018; IRAUy, Montevideo, Uruguay; submitted article). Interestingly, the induction of high progesterone levels for three days before luteolysis (i.e., during the FSH treatment) improves fertilization rate and embryo yield.…”

“…Figure 3. Ovarian superstimulatory treatment (Day 0 protocol) for embryo production in sheep and goats (adapted from Menchaca et al, 2010;Cuadro et al, 2018). During the synchronization period (left), the ovulation is induced to synchronize the emergence of wave 1.…”

“…Figure 4. Embryo cryopreservation by minimum volume vitrification (e.g., Cryotop or Spatula) used in our Laboratory (dos Santos et al, 2015;Meikle et al, 2018;Barrera et al, 2018). Before vitrification (A), the embryos are equilibrated at room temperature with increasing concentrations of cryoprotectants to reach high viscosity.…”

“…This is particularly important in this kind of large-scale projects. Additionally, regarding the relevance of oocyte cryopreservation for different species (Vajta, 2000;Ledda et al, 2007), vitrification by minimum volume methods has been evaluated also in sheep oocytes with promising results (Succu et al, 2008;Barrera et al, 2018). However, even though important advances have been achieved on cryopreservation of in vitro produced embryos and oocytes, further investigations and some refinements are still necessary in order to obtain an easy, fast, low-cost and effective method for a wider application of this ART.…”