Selection of In Vitro-Matured Porcine Oocytes Based on Localization Patterns of Lipid Droplets to Evaluate Developmental Competence

Localization patterns of lipid droplets in the cytoplasm of porcine oocytes wereevaluated as a novel marker for in vitro maturation (IVM) of oocytes withhigh developmental competence. Porcine oocytes were cultured in TCM-199, which is acomplete synthetic medium, for 44 h at 38.5 C. Localization patterns were divided into 2classes: lipid droplets localized uniformly in the whole cytoplasm (class I) and thosethat were centrally located (class II). After IVM in TCM-199, 60% of matured oocytesexhibited the class II pattern. To investigate the relation between the distribution oflipid droplets and the developmental rate of the oocyte, the developmental rates of classI and class II oocytes were compared after in vitro fertilization (IVF).Class II oocytes showed a significantly higher rate of blastocyst development than class Ioocytes. These results suggest that porcine oocytes with high developmental competence canbe selected based on the localization patterns of lipid droplets.