In vitro production of pig embryos: a point of view

Porcine embryos have become raw materials for different programmes of reproductive biotechnology and the in vitro production of embryos has some advantages over in vivo production in gene transfer programmes and for xenotransplantation. Despite this promising future, several problems limit the success of the in vitro production (IVP) of viable porcine embryos. Porcine IVP has not been fully developed because of several problems associated with different techniques, such as incomplete final maturation status after in vitro maturation, a high incidence of polyspermy after in vitro fertilization and a low development rate and poor quality of blastocysts at the end of culture. The results could be improved with studies comparing in vivo and in vitro conditions, standardization of techniques for sperm processing, testing new additives in the culture media and developing intracytoplasmic sperm injection procedures. The first objective of the present article is to summarize the main studies published on the subject. Second, we provide a guide for researchers starting work on the IVP of pig embryos, making special mention of first papers and the most recent achievements for each of the different techniques. Third, we provide suggestions for future experiments designed to improve the results of each technique.