Meiotic block in equine oocytes as an alternative for viability improvement

Abstract

Ultrasound-guided trans-vaginal aspiration is a relatively non-invasive and relatively simple method for repeated punctures of immature and pre-ovulatory follicles in the mare. This technique allows a better use of animals of high genetic and economic value, since with the aid of assisted reproduction techniques, it allows the generation of descendants of elderly animals, with acquired fertility problems, or even from dead animals as well. In these cases it is necessary to transport the oocytes to reproductive centers so that they can be fertilized. The maintenance of these oocytes in meiotic block, either through the use of meiosis inhibitors or keeping them at room temperature, is beneficial for the later embryonic development. In addition, it allows the mare owner more time to decide on the stallion to use and make the semen reach the place. This experiment was designed in order to test the feasibility of maintaining oocytes in a commercial embryonic culture medium available in Brazil or in a culture medium with a meiosis inhibitor, before in vitro maturation. At least 150 oocytes will be analyzed, divided into 3 groups. In Group 1 (G1) oocytes will proceed immediate to maturation with DMEM/F12 medium. In Group 2 (G2) oocytes will remain 20 hours in a commercial medium for embryo transferr (Botuembryo) and In Group 3 (G3), oocytes will be held 20 hours in DMEM/F12 containing Butyrolactone. After the 20-hour period, G2 and G3 will proceed to oocyte maturation with DMEM/F12 medium. The oocytes will be evaluated and classified with respect to nuclear and cytoplasmic maturation and evaluated for gene expression. (AU)