In vitro maturation and fertilization

Abstract Text: Technologies associated with in-vitro maturation (IVM) and fertilization (IVF) of porcine oocytes have been developed with a number of research trials for the past quarter century. However, the efficiency to produce blastocysts in vitro through these technologies is expected to have further drastic improvement for a couple decades. The origin of oocytes, such as sexual maturation of donor females, estrous cycle and follicular size, is known to affect the efficiency of in-vitro embryo production. Brilliant Cresyl Blue assay has also been confirmed to be useful in several species to select cumulus-oocyte complexes (COCs) with a higher developmental competence. To improve the successful rate of embryo production, it is very effective to supplement various factors secreted from oocytes and/or cumulus cells, as well as to regulate cumulus cAMP levels during IVM. Activities of glucose metabolism, fatty acid beta-oxidation and mitochondria during IVM also affect the early development to the blastocyst stage following IVF. Through these modifications, not only COCs from middle-size follicles (MF; 3-6 mm in diameter), but also those from small follicles (SF; 1-3 mm in diameter) have been used for in vitro production of porcine embryos, though the developmental competence of SF oocytes is still lower than those from MF. Efforts to expand gamete resources for IVM-IVF may contribute to prepare materials for bio-engineering and also accelerate genetic improvement in pigs.

Keywords: pig, in vitro maturation, in vitro fertilization