When fertility fails.

International partnership explores mysterious cystic follicles.

An article by Clare Illingworth, SPARK writer, University of Guelph.


Some light may finally be shed on a puzzling fertility problem that has affected humans, cattle and horses for years. Prof. Jim Petrik, Biomedical Sciences, and Nadine G?rard of Equine Repro-duction in France are investigating cystic follicles, a problem in the ovary that causes a halt in the reproductive cycle for 10 to 15 per cent of breeding mares. They’re using the latest in molecular biology techniques and better treatment methods for preven-tion and detection in horses.

“This is a relatively unknown problem, but understanding the biology behind its cause will enable us to develop treatments that work,” says Petrik. Cystic follicles occur when the signals for the follicle (which contains the egg) to ovulate aren’t properly communicated in the mare’s ovary. As the egg develops, it produces estrogen. Rising estrogen reaches a threshold that normally triggers the signal luteinizing hormone (LH) to surge, causing ovulation (when the egg leaves the ovary). Cystic follicles don’t respond to the LH surge and remain on the ovary, halting the reproductive cycle and at times making the mare uncomfortable. The hormonal inconsistencies cause agitation and poor performance. And because a horse’s breeding season is so short, a barren year can mean a huge financial loss to breeders and farms.

Petrik is beginning a four-year study that will compare an existing herd of 25 mares that regularly develop cystic follicles with 25 normally cycling mares. The herd developing cystic follicles is maintained in France by its National Institute of Agricul-tural Research. This herd has an increase in spontaneous formation of follicular cysts, he says. Samples collected in France will be sent to Guelph for analysis and comparison with controls. Petrik will analyse blood and fluid sur-rounding the follicle and the active cells for clues. He’ll use new molecular biology techniques such as DNA microarray, which can test for the presence of 20,000 different genes in one simple procedure.

“We’ll be getting an understanding of the cellular events involved in the formation of follicular cysts,” he says. “We need to know on the basic science level what’s going on before we can prevent or detect the problem.”

Also involved in this research is Hanne Pedersen of the Royal Veterinary and Agri-culture University in Denmark. This study is sponsored by the Ontario Ministry of Agriculture and Food and the Ontario Harness Racing Industry Association.