Analysis of protein synthesis in morphologically classified bovine follicular oocytes before and after maturation in vitro

Publisher Website
Google Scholar
Abstract
Bovine cumulus oocyte complexes (COCs) were isolated from antral ovarian follicles (4–8 mm). Immature COCs were classified into four categories, based on the homogeneity and clearness of the ooplasm and the transparency and compactness of the cumulus investment. In this study, the incorporation of TCA‐precipitable 35S‐methionine and the protein synthesis patterns of oocytes of these four categories were examined. Before maturation in vitro, similar incorporation rates and identical protein synthesis patterns were observed between oocytes of categories 1–3. Immature oocytes of category 4 showed reduced incorporation rates and exhibited aberrant protein synthesis patterns. After maturation in vitro, the patterns of category 4 oocytes were identical with the patterns of those in categories 1–3. The incorporation of 35S‐methionine into in vitro matured oocytes was lower (P < .001) in all categories.Based on these results, it is concluded that the initial classification of oocytes into four categories can be reduced to two categories.