A combination of EGF and IGF-I accelerates the progression of meiosis in bovine follicular oocytes in vitro and fetal calf serum neutralizes the acceleration effect
M. Sakaguchi et al., A combination of EGF and IGF-I accelerates the progression of meiosis in bovine follicular oocytes in vitro and fetal calf serum neutralizes the acceleration effect, THERIOGENOL, 54(8), 2000, pp. 1327-1342
The effects of a combination of EGF and IGF-I (GFs) on the progress of meio
sis and on their developmental competence were examined in cumulus-enclosed
bovine oocytes. Exposure to GFs in serum-free, 0.3% PVP-containing maturat
ion medium significantly (P<0.05) increased the frequency of oocytes with t
he first polar body (PB) at 16 h of culture and decreased those with PB at
20 h. The cleavage rates of PB-extruded oocytes after fertilization were no
t affected by treatment of GFs during maturation culture, and blastocyst yi
eld was not improved by GFs treatment. Although replacement of PVP from GFs
-containing medium with fatty acid-free BSA did not affect the timing of PB
extrusion, replacement with 10% FCS neutralized the acceleration effects o
f GFs. Replacement for macromolecule in maturation medium did not improve b
lastocyst yield of PB-extruded oocytes after fertilization. These results i
ndicate that the progression of meiosis in bovine oocytes with cumulus cell
s is accelerated by exposure to GFs in serum-free maturation medium but the
ir developmental competence is not improved, and that the acceleration effe
cts on the progress of meiosis is neutralized by the presence of FCS in mat
uration medium with no improvement of developmental competence after in vit
ro fertilization. (C) 2000 by Elsevier Science Inc.