PARENT SESSION

(M382) DEVELOPMENTAL POTENTIAL OF BOVINE OOCYTES CULTURED IN DEFINED MATURATION MEDIA.

Sagirkaya, Hakan^{1, 2}, Misirlioglu, Muge¹, Kaya, Abdullah³, Odaman-Mercan, Hande¹, First, Neal³, Parrish, John³, Memili, Erdogan¹, ¹ Mississippi State University, Mississippi State, MS² Uludag University, Bursa, Turkey³ University of Wisconsin-Madison, Madison, WI

ABSTRACT- Optimized in vitro production (IVP) procedures frequently include supplements such as serum and/or co-culture with various types of somatic cells. However, effectiveness of serum in in vitro maturation (IVM) and fertilization (IVF) might change considerably from one batch to another. In addition, use of undefined serum may cause problems during fetal development. The objective of this study was to investigate the possibility of using synthetic serum substitute (SSS, Irvine Scientific) in place of fetal calf serum (FCS) in maturation medium to stimulate IVM, IVF and subsequent embryo development. Ovaries were obtained from a local abattoir. Oocytes with several layers of cumulus cells were matured in three different conditions in terms of serum supplementation. Tissue culture medium 199 (TCM 199) supplemented with 0.25 mM Na-pyruvate, 0.5 mg/ml of FSH, 5 mg/ml of LH, 100U/ml Penicillin and 100 mg/ml of Streptomycin was used for all of the groups. Oocytes were matured in TCM 199 medium as Control Group, Groups I and II supplemented with 10% FCS, 10% SSS and 10% SSS + 10 ng/ml EGF, respectively. Oocytes matured twenty-four hours were in vitro fertilized (day 0) using frozen bull sperm. Presumptive zygotes were transferred into synthetic oviductal fluid (SOF) medium 12-14 hours post insemination (hpi), and supplemented with 10% FCS on day 4, and cultured until day 9. Groups of blastocysts were fixed and stained for total cell count on day 7. In three separate trials, a total of 439, 395 and 415 oocytes were used for Control Group, Groups I and II, respectively. Cleavage rates were 76.2, 74.6 and 78.4%, and rates of development to blastocyst stage were 29.1, 28.5 and 29.2% for Control Group, Groups I and II, respectively. There was no statistical difference among cleavage rates and rates of development to blastocyst stage. Mean cell numbers were 122.3, 90.0 and 105.6 for Control Group, Groups I and II, respectively. Cell numbers differed only between Control Group and Group II (P<0.05). These results show that SSS and EGF might be successfully used in the maturation medium instead of fetal calf serum and they support development until blastocyst stage. Expression profiles of key developmentally regulated genes in these blastocysts are currently under investigation.

KEY WORDS: bovine, IVP, synthetic serum