In vitro maturation of equine oocytes obtained from different age groups of sexually mature mares

S. P. Brinsko, B. A. Ball, J. E. Ellington

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26 Scopus citations


Oocytes were harvested from mare ovaries obtained at slaughter and were divided into 3 groups based on the age of the donor. The age groups consisted of young (2 to 7 yr), middle-aged (8 to 14 yr) and aged (≥15 yr) mares. There were no differences between age groups in the proportions of follicles available for examination or the proportions of normal, abnormal or total oocytes collected. After 24 h of culture, the overall maturation rate to the second metaphase (MII) was 52.7%. Maturation rates for oocytes obtained from young and middle-aged mares were similar, but oocytes from aged mares were only ~25% as likely to reach MII and they were 3 times more likely to remain at metaphase I. Twelve oocytes had chromosome spreads suitable for counting; 6 were haploid, 2 were hyperhaploid and 4 were hypohaploid. Insufficient numbers of readable spreads precluded comparisons of chromosome complements between age groups.

Original languageEnglish
Pages (from-to)461-469
Number of pages9
Issue number4
StatePublished - Sep 1995

Bibliographical note

Funding Information:
Evidence from several studies involving a number of different species indicates that the quality of ova deteriorates in aging animals and results in an increased incidence of abnormal ova and developmental failure (reviewed by 2). The use of assisted reproductive technologies has provided a large amount of data indicating that the oocyte is a primary cause of decreased reproductive capacity in older women. In a number of human IVF studies, the age-related decline in female Acknowledgments This study was supported by USDA grant #91-37203-6552. S.P. Brinsko was the recipient of a Graduate Research Assistantship awarded by the College of Veterinary Medicine, Cornell University. We would liie to thank Dr. W.A. King at the University of Guelph for providing advice and laboratory facilities as well as Dena Shepard, Nancy Hazeleger and Paula Miller for their technical assistance. We would also like to thank Agriculture Canada and Barton Feeders, Owens Sound, Ontario, Canada for allowing collection of the tissues. ’ Correspondence and reprint requests, ’ Current address: Health Research Education Center, Washington State University, West 601 1s t Avenue, Spokane, WA 99204.


  • age
  • equine
  • in vitro
  • maturation
  • oocyte

ASJC Scopus subject areas

  • Small Animals
  • Food Animals
  • Animal Science and Zoology
  • Equine

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