P-32: Cumulus Cell Features and Nuclear ChromatinConfiguration of In vitro Matured CanineCOCs and the Influence of In vivo Serum ProgesteroneConcentrations of Ovary Donors

Background: The objectives of this study were: a) to observe the influence of cumulus investment expansion on the nuclear chromatin configuration of canine oocytes matured in vitro; b) to examine the relationship between cumulus cell (CC) expansion and its morphology after in vitro maturation (IVM); c) to ascertain the influence of in vivo serum progesterone (SP) concentrations of ovary donors on oocyte nuclear maturation, CC phenotypes and degrees of CC expansion of in vitro matured COCs. Materials and Methods: After 48 h of IVM in modified TCM 199, CCs from grade 1 and 2 COCs were stained with propidium iodide. Oocyte chromatin configuration was visualized by Hoechst 33342 stain. Results: The results showed that oocyte IVM was not influenced by degree of CC expansion (D1, D2, and D3) in COCs. From the CC types (C1, C2, and C3), number of C1 types was higher at D1 expansion and differed from those observed at D2 and D3 expansions. Additionally, rates of apoptosis in D1 CCs were lower than those observed in D2 CCs (p 2.5 ng/ml (p5 ng/ml) in vivo SP levels.Conclusion: These findings indicate that morphology of CCs from in vitro matured dog oocytes gives valuable information on viability of COCs and could possibly be used as a parameter in predicting the quality of oocytes destined for in vitro fertilization (IVF) and their outcomes.