Molecular aspects of cytoplasmic and nuclear maturation of pig oocytes

The development of pig reproductive biotechnology has made it possible to use this species not only as farm animals but also as important models in biomedical research. Systems based on pig embryos from in vitro fertilization (IVF) are used much more frequently, although the quality of these embryos differs from those produced by in vivo fertilization. The most frequent problems in the IVF procedure are disturbances in both nuclear and cytoplasmic oocyte maturation, and the mechanism of polyspermy specific for this species. Although there has been progress in increasing the number of oocytes produced by in vitro maturation processes, the quality of embryos from these oocytes and their developmental competence is still unsatisfactory. It has been suggested that the most important factor in this process is the establishment of optimal conditions for the development and maturation of oocytes. In this review the authors attempt to explain the molecular basis of oocyte maturation, meiosis resumption, and meiotic spindle assembly. The article is also an opportunity to use the knowledge gained to date in order to increase the efficiency of animal breeding, to evaluate the genetic value of oocytes, as well as to improve assisted reproductive techniques (ART).