Postovulatory effect of repeated administration of prostaglandin F 2a on the endocrine status, ova transport, binding of accessory spermatozoa to the zona pellucida and embryo development of recently ovulated sows A.M. Mwanza a,1 , S. Einarsson a,* , A. Madej b , N. Lundeheim c , H. Rodriguez-Martinez a , H. Kindahl a a Department of Obstetrics and Gynaecology, Centre for Reproductive Biology in Uppsala (CRU), Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, Box 7039, SE-750 07 Uppsala, Sweden b Department of Animal Physiology, Centre for Reproductive Biology in Uppsala (CRU), Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden c Department of Animal Breeding and Genetics, Centre for Reproductive Biology in Uppsala (CRU), Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden Received 15 March 2001; accepted 4 June 2001 Abstract WeinvestigatedthepostovulatoryeffectofrepeatedadministrationofprostaglandinF 2a (PGF 2a )on the endocrine status, ova transport, binding of accessory spermatozoa to the zona pellucida (ZP) and embryo development of recently ovulated sows. We used altogether 10 Swedish crossbred (Landrace  Yorkshire) multiparous sows. The treatment group (P-group) was administered 1mg ofPGF 2a intravenouslyevery6hviaanindwellingjugularcannula,commencing4±8hafterovulation was detected in the second estrus after weaning. All sows were inseminated once and blood was sampled until the end of the experimental period. After slaughter, we immediately recovered the reproductive tracts and divided them into three equal isthmic segments (IST1, IST2 and IST3) and a thirdoftheuterinehornfromtheutero-tubal-junction(UTJ),andwe¯ushedeachonewithPBSforova recovery.Weimmediatelystainedtheovaandexaminedthemunderepi-¯uorescenceillumination.We found the highest proportion of ova in the P-group in IST1 (41.5%), while we found the highest Theriogenology 58 (2002) 1111±1124 * Corresponding author. Tel.: 46-1867-2170; fax: 46-1867-3545. E-mail address: stig.einarsson@og.slu.se (S. Einarsson). 1 Present address: Department of Clinical Studies, School of Veterinary Medicine, University of Zambia, Box 32379, Lusaka, Zambia. 0093-691X/02/$ ± see front matter # 2002 Elsevier Science Inc. All rights reserved. PII:S0093-691X(02)00651-9