کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2096125 | 1082154 | 2007 | 5 صفحه PDF | دانلود رایگان |
Canine cumulus-oocyte complexes (COC) were recovered from ovaries of post-pubertal animals (1–3, 4–6 and 7–10 years old) at different ovarian estrous phases (anestrus and diestrus). The number of COCs, and the number and nuclear maturity of high-quality (grade-1) oocytes were assessed. For all animals, no significant differences were found between the two reproductive phases relatively to the total number of COCs and grade-1 oocytes recovered. However, significant higher numbers of COCs were recovered from young than from elderly animals, and the proportion of grade-1 oocytes was also significantly higher in the younger group than in the other two age-groups. Of 226 grade-1 oocytes, 73% were at the germinal vesicle stage (GV), 10% had resumed meiosis (9% at germinal vesicle breakdown; 1% at metaphase-I) and 17% were degenerated. A significant effect of the reproductive phase on oocyte nuclear maturity was found only for adult animals, with a higher number of GV oocytes being found at anestrous (79%) due to higher rates of meiosis resumption (34%) at diestrous. The high number of grade-1 oocytes with meiosis resumption and fragmented or unidentified nuclear contents, indicates that current criteria for the selection of viable canine COCs are not optimized and need a new definition.
Journal: Theriogenology - Volume 68, Issue 6, 1 October 2007, Pages 821–825