Effect of Dibutyryl cAMP Together with FSH and EGF during In Vitro Maturation on Sperm Aster Formation and Blastocyst Development after Intracytoplasmic Sperm Injection

抄録

Bovine intracytoplasmic sperm injection (ICSI) is a useful technique in the production of calves. Generally, oocytes matured in vitro are used for bovine ICSI, but the developmental competence is lower than that of oocytes matured in vivo. The objective of this study was to evaluate the effect of dibutyryl cAMP (dbcAMP) during in vitro maturation (IVM) on meiotic maturation, sperm aster formation, and blastocyst development after ICSI. Cumulus-oocyte complexes were cultured in TCM199 supplemented with 100 μM dbcAMP in the presence or absence of follicle-stimulating hormone (FSH) and epidermal growth factor (EGF) in the following treatment four groups: an untreated control, dbcAMP, FSH/EGF, and FSH/EGF/dbcAMP. The percentage of MII oocytes at 21 h did not differ among the four groups (66.7–73.9%). The percentages of sperm aster formation in the FSH/EGF and FSH/EGF/dbcAMP groups (87.1% and 85.7%, respectively) and the diameter of sperm asters in the FSH/EGF/dbcAMP group (81.6 ± 2.7 μm) were significantly greater than those in the other groups. The blastocyst rate in the FSH/EGF/dbcAMP group (42.7%) was significantly greater those that in the other groups. Thus, adding dbcAMP together with FSH and EGF to IVM medium stimulated the sperm aster formation in bovine oocytes and increased the blastocyst rate after ICSI.