Effect of corpus luteum on the number and classification of follicles and Oocytes in the ovaries of local ewes (Ovis aries)

Abstract

The aim of current study to estimate effect of corpus luteum (CL) on the number and classification of follicles and oocytes in the ovaries of local ewes (Ovis aries) during September 2021 to February 2022.  The genital organs of 524 for adult non-gravid ewes slaughtered in the slaughterhouse in Al-Najaf government were collected and transferred to the laboratory within two hours. The ovaries (n=1048) were removed and divided in to the ovaries bearing CL (n=166) and without CL (n=882). Follicles were calculated, measured and categorized in to three categories, small (<3mm), medium (3-5mm), and large (>5mm). The oocytes were collected, examined, calculated, evaluated and graded into three degrees depending on the number of cumulus cells layers, homogenous of cytoplasm and oocyte morphology. The results showed that the number of follicles (n=4422) and the average number of follicles per ovary (5.01±0.04) were significantly (p<0.01) increased in the ovaries without CL when than the ovaries with CL.A Significantly (P<0.01) higher the number of follicles for all follicle sizes in the ovaries non-bearing CL compared to those bearing CL. A greater number of oocytes (n=2771) and the average number of oocytes per ovary (3.14±0.06) were found in non-bearing CL ovaries than those bearing CL ovaries (n=406 and 2.44±0.04 respectively). The number of first and second degrees of oocytes were significantly (p<0.01) increased in the ovaries without CL than those with CL. Thus on the basis of our results it can be concluded that the presence of CL have negatively and harmful effect on the number of follicles and oocytes and oocytes quality.