Microtubule assembly crucial to bovine embryonic development in assisted reproductive technologies

Centrosome integrity and microtubule network are crucial to the events around fertilization, including pronuclear development, migration and fusion, and the first mitotic division. The present review highlights the importance of bull spermatozoal centrosomes to function as a microtubule-organizing center for successful fertilization and the subsequent embryonic development. Spermatozoal centrosomes need to be blended with ooplasmic pericentriolar materials accurately to nucleate and organize the sperm aster. Dysfunction of the spermatozoal centrosomes is associated with fertilization failure, which has been overcome with supplemental stimuli for oocyte activation following intracytoplasmic sperm injection in humans. Even though the spermatozoal centrosomes are functionally intact, abnormal sperm aster formation was frequently observed in vitrified-warmed bovine oocytes, with delayed pronuclear development and migration. Treatment of the post-warm oocytes with Rho-associated coiled-coil kinase inhibitor or α-tocopherol inhibited the incidence of the abnormal aster formation, resulting in higher blastocyst yields following in vitro fertilization and culture. Thus, understanding of centrosomal function made it possible to improve the performance of advanced reproductive technologies.