Effects of different insulin concentrations on in vitro maturation of bovine oocyte in the presence and absence of cumulus cells

This study investigated the effect of various insulin concentrations on the maturation of Bovine oocyte with cumulus and stripped cumulus. In the cumulus group, aspirated oocytes had at least three layers of cumulus. The oocytes were collected from 2-8 mm follicles of the bovine ovary from a slaughter house and transferred to the maturation media after being washed three times in the rinsing medium. The oocytes with and without cumulus were divided into two sets of four groups including the control group, which did not receive any insulin, and groups receiving 0.1, 1, and 10 μg/ml insulin. The maturation media were incubated at 38.5°C with 5% carbon dioxide for 22-24 hours. After incubation, the cumulus around the oocytes was removed in the cumulus-containing groups and evaluated for polar body expulsion. The analysis showed that the oocyte maturation in the groups containing higher concentrations of insulin was significantly higher. Also, in the group where oocyte was kept in the culture medium with cumulus cells, the maturation was significantly higher than the group without cumulus cells. Finally, it can be concluded that increased insulin concentration in the presence of cumulus cells can improve the efficiency of oocyte maturation medium in dairy cattle.