This study evaluated the effect of epidermal growth factor (EGF) supplementation during in vitro maturation on the meiotic status and the expression of EGF receptor (EGFr), luteinizing hormone receptor (LHr) and gap junction protein α 5 (GJA5) in canine cumulus-oocyte-complexes (COCs). COCs of ≥110 μm diameter, exhibiting dark pigmentation and completely surrounded by three or more layers of cumulus cells collected from anestrus stage ovaries in natural cycle were matured in TCM-199 supplemented with 10% fetal bovine serum, 0.57 mM cysteine, 10 μg/ml LH and FSH, and different concentrations of EGF (0, 10 and 30 ng/ml). Oocytes cultured for 72 h were fixed to assess the nuclear maturation. Expression of EGFr, LHr and GAJ5 was assessed by immunocytochemistry and real-time PCR. Proportion of metaphase II status of oocytes cultured in in vitro maturation (IVM) medium supplemented with 10 ng/ml EGF for 72 h was significantly (P<0.05) higher than 0 and 30 ng/ml EGF supplemented IVM medium (9.8% vs. 6.5% and 5.2%). In both cumulus cells and oocytes, EGFr protein was undetectable, LHr protein level of expression was low and a strong expression of GJA5 protein was observed. The relative abundance (RA) of EGFr transcript revealed low levels and the LHr expression decreased steadily with addition of EGF. However it did not vary among different concentrations of EGF supplementation. The RA of GJA5 transcript exhibited lower level at 10 ng/ml EGF supplementation. In conclusion, the supplementation of 10 ng/ml EGF in IVM media exerted a positive influence on the progression of maturation to MII phase and the expression level of GJA5 at 72 h, but did not demonstrate any stimulatory role on the expression of EGFr and LHr during the maturation of the canine IVM oocytes.
"SDF-1a is believed to promote T-cell recruitment and granulosa cell survival, thereby creating an environment favourable to oocyte maturation; thus, in this respect, SDF-1a may have potential as a candidate biomarker of oocyte maturation and fertilisation (Kryczek et al., 2005). As outlined earlier, EGF and EGF-like peptides have been implicated in oocyte maturation in vivo, as reflected by the fact that these are frequently used as culture medium supplements to promote in vitro maturation of germinal vesicle-stage oocytes in various mammalian species (Park et al., 1997; Goud et al., 1998; Merriman et al., 1998; Oyamada et al., 2004; Merlo et al., 2005; Bolamba et al., 2006; Lee et al., 2011; Song et al., 2010; "
"Indeed, the metabolism of lipids represents the main energy source for protein synthesis during oocyte nuclear maturation and early embryo development [34, 35]. Simultaneously, adequate communication between oocyte and CCs and appropriate assembly and organization of the CC matrix are required for both oocyte maturation and competence [36–38]. Most of the genes, identified in the present investigation as differentially expressed in CCs treated with HP-hMG and rFSH, were reported for the first time, except for TNFAIP6 and GJA5 (connexin 40) which have been previously identified as potential markers of oocyte competence in CCs from bovine preovulatory follicles  and biomarker of oocyte maturation in canine cumulus-oocyte complexes matured in vitro, respectively . "
[Show abstract][Hide abstract] ABSTRACT: In in vitro fertilization cycles, both HP-hMG and rFSH gonadotropin treatments are widely used to control human follicle development. The objectives of this study are (i) to characterize and compare gene expression profiles in cumulus cells (CCs) of periovulatory follicles obtained from patients stimulated with HP-hMG or rFSH in a GnRH antagonist cycle and (ii) to examine their relationship with in vitro embryo development, using Human Genome U133 Plus 2.0 microarrays. Genes that were upregulated in HP-hMG-treated CCs are involved in lipid metabolism (GM2A) and cell-to-cell interactions (GJA5). Conversely, genes upregulated in rFSH-treated CCs are implicated in cell assembly and organization (COL1A1 and COL3A1). Interestingly, some genes specific to each gonadotropin treatment (NPY1R and GM2A for HP-hMG; GREM1 and OSBPL6 for rFSH) were associated with day 3 embryo quality and blastocyst grade at day 5, while others (STC2 and PTX3) were related to in vitro embryo quality in both gonadotropin treatments. These genes may prove valuable as biomarkers of in vitro embryo quality.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to evaluate the effect of epidermal growth factor (EGF) on the rate of maturation of bovine oocytes cultured in vitro in a chemically defined maturation medium. Four hundred eighty four slaughterhouse ovaries oocytes were used, where the base medium was TCM 199 supplemented with sodium pyruvate, 17 β estradiol, gentamicin. Four treatments were randomly formed: T1: no EGF (Control), T2: 1 ng of EGF, T3: 10 ng of EGF and T4: 50 ng of EGF. The results indicate that significant difference (P<0.05) of EGF on the proportion of oocytes, there was a higher proportion of oocytes that reached metaphase II status to the concentration of 50 ng/mL of EGF (73%), followed by 10 ng/mL (54.2%), and 1 ng/mL of EGF (32.3%). However, among the control medium and the supplemented with 50 ng/mL of EGF were no significant differences (70.3 -73%, respectively), indicating that both means favor the maturation of oocytes. In conclusion, the supplementation of chemically defined maturation medium showed no stimulatory effect of EGF on the percentage of metaphase II oocytes from of bovine ovaries collected post mortem.
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