Factors and methods of pig oocyte and embryo quality improvement and their application in reproductive biotechnology.

Compared to other mammalian species, pig oocytes and embryos are characterized by high lipid contents stored mainly as lipid droplets in the cytoplasm. This fact has a negative influence on manipulations on oocytes and embryos and, in general, biotechnological procedures are much less advanced in pigs than in cows. This paper discusses current methods for modifying porcine oocytes and embryos using in vitro culture or microsurgical manipulation, chemical agents such as cytochalasin B or D, physical means such as centrifugation or increased pressure and the biotechnological implications of these procedures. The presented methods make it possible to modify the characteristics of oocytes and embryos and thus increase their susceptibility to cryopreservation and cloning.