Abstract
Morphological characteristic is the primary reference for selecting viable cumulus-oocyte-complex (COCs). Annexin-V assay has been suggested for isolating these viable cells based on apoptosis status. This study compared fertilization rate between Annexin-V selected COCs with morphologically healthy selected COCs. Minimal binding time between Annexin-V and the COCs was determined to ensure slight disruption. Before observation with florescent microscope, eighty-two cattle’s COCs were incubated with the Annexin-V assay for 5 min, 15 min and 24 hours. Further, 157 COCs were separated into 2 groups; positively (n=76) and negatively (n=81) tagged with annexin-V-FITC and PI fluorescent signals. Once separated, control comprised of non-stained COC (n=68) and the two afore mentioned groups were matured, fertilized and cultured (IVM-IVF-IVC). After 72 hpi, cleavage rate was determined. Results shows the binding between annexin-V assay and the nonviable COC had occurred as early as 5 min with positively and negatively tagged COCs were 44 (53.7%) and 38 (46.3%) respectively. The fertilization rate of control group (66%), negatively tagged (79%) and positively (50%) tagged COCs was significantly different (?² (2) = 14.60, p < 0.05) between the groups. In conclusion, oocyte selection using annexin-V-FITC had significant differences in cleavage rate compared with oocytes assumptive as morphologically healthy. Based on COCs Annexin-V assay, COC that are assumed as morphologically healthy is a mixture of viable and nonviable oocytes.
Highlights
Viable oocyte selection prior to maturation process is an important step in achieving high successful in vitro fertilization rate (Camargo et al, 2006)
Control comprised of non-stained COC (n=68) and the two afore mentioned groups were matured, fertilized and cultured (IVM-In vitro fertilization (IVF)-In vitro Culture (IVC))
Oocyte selection using annexin-V-fluoroscein isothiocyanate (FITC) had significant differences in cleavage rate compared with oocytes assumptive as morphologically healthy
Summary
Viable oocyte selection prior to maturation process is an important step in achieving high successful in vitro fertilization rate (Camargo et al, 2006) To date, this selection of viable oocytes is solely based on morphological assessment (Plourde et al, 2012). COCs that morphologically identified as early signs of atresia in contrast had shown good nuclear maturation and development potential than those considered to be morphologically viable (Bilodeau-Goeseels, 2001; De Wit, Wurth, & Kruip, 2000). This assessment takes longer time to assess especially when it involves high number of sample to be assessed in one particular day. Any further delay in placing the COC into the nutrient media for the maturation process will result in failure of fertilization
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