Oocyte cryopreservation has become a practical tool in assisted reproductive technology and fertility preservation. Cryoprotective agents (CPAs) addition and removal are essential steps during oocytes cryopreservation

however

the processes of CPAs addition and removal may cause fatal osmotic and toxic injuries to oocytes. In order to study the injuries of porcine MII-stage oocytes during CPAs addition and removal combined processes and minimize osmotic and toxic injuries to oocytes

primarily

a microfluidic device for continuous loading and unloading of CPAs was designed and fabricated in this study. CPAs were loaded and unloaded with the microfluidic linear method and the conventional step-wise method

respectively. Then

the cell volume changes and the effects on the survival rate and developmental potential of oocytes were investigated. The results showed that the oocyte volume changes with the microfluidic device were obviously less than step-wise method. The survival

cleavage and blastocyst rate of oocytes were 95.3%

64.4%

and 19.4%

respectively

which were significantly higher than the traditional step-wise method (79.4%

43.6%

and 9.7%) (P<0.05). In conclusion

microfluidic device can be used efficiently to load and unload of CPAs

and significantly reduce the osmotic shock to oocytes

which may open up a new path for oocyte cryopreservation.