Theriogenology In-vitro Culture with a tilting device in chemically defined media during meiotic maturation and 5 early development improves the quality of blastocysts derived from in-vitro matured and fertilized porcine oocytes

25 In the physiological condition, mammalian oocytes and embryos appears to be stimulated not only chemically but also mechanically, such as compression, shear stress and/or friction force in the follicle and female reproductive tract. The present study was undertaken to examine the effects of kinetic culture with a tilting device in chemically defined media during in vitro maturation (IVM) of porcine oocytes and the in vitro culture (IVC) following in vitro fertilization (IVF) on the 30 early developmental competence and the quality of blastocysts. After culture in a chemically defined IVM medium, modified porcine oocyte medium (mPOM) containing gonadotropins and dibutyryl cAMP for 20 h, the mean diameter of cumulus-oocyte complexes (COC) was larger in tilting culture than static controls, whereas the diameter of oocytes did not differ. When the COC were continued culture additionally in a fresh medium without gonadotropins and dibutyryl cAMP 35 for 24 h, the incidences of oocytes completing GVBD and developed to the metaphase-II stage did not differ between tilting and static culture systems. Furthermore, the developmental competence of the oocytes to the blastocyst stage in a chemically defined medium following IVF was also not different between tilting and static systems. However, tilting culture during both IVM and in-vitro culture following IVF significantly affected positively the number of cells in a blastocyst (p<0.05). 40 These observations indicate that tilting culture during IVM and the in vitro culture following IVF in chemically defined media improves the quality of blastocyst, as determined the number of cells per blastocyst, without any effects on the developmental competence.