STUDY ON CORTICAL GRANULES CHANGE OF PIG OOCYTES DURING IVM AND IVF

Objective\ To investigate the behavior of cortical granules(CGs) during IVM and IVF, and the relationship between CGs and polyspermy. Methods\ We used the FITC\|PNA as a probe to label the different period of IVM and IVF pig oocytes. Results\ CGs migrate towards the cell membrane during IVM, and finally form a monolayer under the membrane. The first polar body can be labeled by FITC\|PNA indicating that it contains CGs. After fertilization oocytes maured in vitro, the speed of CGs release is in proportion with maturation time. To confirm the relationship of CGs exocytosis speed with polyspermy, we tested the sperm penetration on the oocytes matured in vitro for different period of time. In oocytes matured in vitro for 48h, polyspermy ratio is 73%, and lower than that in 36h(83%)and 24h(80%). Number of penetrating sperm(1\^7)in 48h matured oocytes is also lower than that in 36h(3\^1)and 24h(2\^9). Conclusion\ The polyspermy incidence has a direct relation with the speed of CGs exocytosis and its quantity.\;