1. Department of Animal Reproduction, Section of Andrology, School of Veterinary Medicine, SAREC Interuniversity Cooperation Program, Universidad Nacional, P.O Box 304-3000, Heredia, Costa Rica
2. Department of Obstetrics and Gynaecology, Faculty of Veterinary Medicine, Centre for Reproductive Biology (CRB), Swedish University of Agricultural Sciences, (SLU), P.O. Box 7039, SE-750 07 Uppsala, Sweden