Abstract
There are only limited informations available for essential factors which lead to attain complete growth of bovine oocytes derived from early antral follicles. This study was designed to examine factor(s) necessary for achieving full growth of bovine oocytes from early antral follicles. The effect of keratinocyte growth factor (KGF) on the stimulation of the oocyte growth and development was investigated in a culture of cumulus-oocyte complexes with granulosa cells (COCGs) for up to 16 days. A high proportion of COCGs with normal morphology could be maintained even in the control growth medium, and the addition of KGF showed no further increase in the proportion of COCGs with normal morphology. However, the mean oocyte diameter of COCGs was significantly increased in the KGF-containing medium compared to the control after 16 days. After a subsequent in vitro maturation, the in vitro grown oocytes treated by KGF apparently increased the rate of meiotic competence as indicated by an increase in the number of oocytes reaching the M II phase as compared to the control. Furthermore, the in vitro grown oocytes cultured in KGF-containing medium resulted in high rate of developmental competence after in vitro maturation, in vitro fertilization and in vitro embryo culture. These results strongly suggest that KGF may be an important regulator for growing oocytes to reach their full growth potential.
