J Vet Sci.  2004 Sep;5(3):247-251.

Thickness of cumulus cell layer is a significant factor in meiotic competence of buffalo oocytes

Affiliations
  • 1Department of Theriogenology, Faculty of Veterinary Sciences, University of Veterinary and Animal Sciences, Lahore 54000, Pakistan.
  • 2Andrology and IVF Laboratories, School of Medicine, University of Utah, 675 Arapeen Drive, Suite 205, Salt Lake City, UT 84108, USA. kazimchohan@hotmail.com

Abstract

This study evaluated the meiotic competence of buffalo oocytes with different layers of cumulus cells. A total of 588 oocytes were collected from 775 ovaries averaging 0.78 oocytes per ovary. Oocytes with homogenous cytoplasm (n = 441) were selected for in vitro maturation (IVM) and divided into four groups based on their cumulus morphology: a) oocytes with > or == 3 layers of cumulus cells, b) 1-2 layers of cumulus cells and oocytes with partial remnants or no cumulus cells to be cocultured c) with or d) without cumulus cells. Oocytes in all four groups were matured in 100 microL drop of TCM-199 supplemented with 10microgram/mL follicle stimulating hormone (FSH), 10microgram/mL luteinizing hormone (LH), 1.5microgram/mL estradiol, 75microgram/mL streptomycin, 100 IU/mL penicillin, 10 mM Hepes and 10% FBS at 39degrees C and 5% CO2 for 24 hours. After IVM, cumulus cells were removed from oocytes using 3 mg/mL hyaluronidase, fixed in 3% glutaraldehyde, stained with DAPI and evaluated for meiotic competence. The oocytes with > or ==3 layers of cumulus cells showed higher maturation rates (p <0.05: 64.5%) than oocytes with partial or no cumulus cells (8.6%) and oocytes co-cultured with cumulus cells (34.5%) but did not differ from oocytes having 1-2 layers of cumulus cells (51.4%). The degeneration rates were higher (p < 0.05) for oocytes with partial or no cumulus cells (51%) than rest of the groups (range: 13.8% to 17.4%). These results suggest that buffalo oocytes with intact layers of cumulus cells show better IVM rates than oocytes without cumulus cells and the co-culture of poor quality oocytes with cumulus cells improves their meiotic competence.

Keyword

buffalo; oocyte; cumulus; IVM

MeSH Terms

Animals
Buffaloes/*physiology
Female
Fluorescent Dyes/chemistry
Indoles/chemistry
Meiosis/*physiology
Microscopy, Fluorescence/veterinary
Oocytes/cytology/growth&development/*physiology
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