Abstract: Oocyte activation deficiency (OAD) refers to the failure of the evoking calcium oscillations which orchestrates a series of key events, such as the resumption of meiosis, extrusion of polar body, exocytosis of cortical granules and the formation of pronuclei after the spermatozoon is engulfed by the oocyte cytoplasm. These events are essential for the following embryogenesis. Both the defect of sperm and oocyte may cause OAD. Assisted oocyte activation (AOA) and the recombinant protein recombinant human phospholipases C zeta (rhPLCζ) injected into oocyte can significantly improve the fertilization outcome of OAD oocyte undergoing intracytoplasmic sperm injection (ICSI). In this paper, the causes and countermeasures of OAD were discussed.

Key words: Sperm injections, intracytoplasmic, Fertilization in vitro, Calcium signaling, Oocyte activation, Phospholipases C zeta