Oocyte Quality and Subsequent In Vitro Maturation of Sheep Oocyte-Cumulus Complex from Ovary with Presence and Absence of Corpus Luteum

Abstract

In vitro maturation is the crucial step for in vitro embryo production. It needs a large number of oocytes as source gamet cells recovered. The present study is aimed to assess the influence of corpus luteum on the average number oocytes harvested, COCs quality and subsequent maturation of immature oocytes recovered from sheep ovaries. Sheep ovaries were collected from local slaughterhouse and COCs were collected by using slicing method. Collected COCs were graded into three categories dependent upon cumulus cells surrounding them and the homogenous of cytoplasm. COCs were maturated in maturation media at 5% CO2 for 24 hours. Maturation of oocytes evaluated base on the expansion of cumulus cells and extrusion of the first polar body. There was significantly higher on average of COCs harvested from ovaries with corpus luteum compared without corpus luteum. The presence of Corpus luteum did not affect the COCs quality and ability to reach the maturation stage. However, there was a dramatic effect of cultured COCs quality on maturation rate both groups. Collectively, these results indicate that COCs quality is the main factor affecting the subsequent of oocytes matured in vitro. Keywords: Corpus luteum; cumulus oocyte complex; in vitro maturation; maturation rate; ovaries