Animal Reproduction Science 117 (2010) 160–165 Contents lists available at ScienceDirect Animal Reproduction Science journal homepage: www.elsevier.com/locate/anireprosci Effects of estrous cycle stage and transport temperature of ovaries on in vitro maturation of canine oocytes Mithat Evecen a , Ümüt Cirit a,∗ , Kamber Demir a , Özen Banu Özdas ¸ a , Muzaffer Tas ¸ b , Sema Birler a , Serhat Pabuccuo˘ glu a a Department of Reproduction and Artificial Insemination, Faculty of Veterinary Medicine, Istanbul University, 34320 Avcilar, Istanbul, Turkey b Department of Reproduction and Artificial Insemination, Faculty of Veterinary Medicine, Dicle University, 21280 Diyarbakir, Turkey article info Article history: Received 3 September 2008 Received in revised form 23 February 2009 Accepted 13 March 2009 Available online 24 March 2009 Keywords: Canine Ovary Estrous cycle stage Transport temperature In vitro maturation abstract Unlike other domestic animals, in vitro maturation (IVM) of canine oocytes still has limited success. The present study investigated the effects of estrous cycle stage and transport temperature of ovaries on in vitro maturation of canine oocytes. The donor bitches were categorized into three groups based on stage of estrus cycle: follicular (proestrus or estrous), luteal (diestrus) and anestrus. One ovary of each pair collected from 39 mature bitches was transported in Phosphate Buffer Saline (PBS) at 4 ◦ C while the other was transported at 37 ◦ C. A total of 1138 Grade I COCs obtained from all ovaries were grouped and matured in modified synthetic oviduct fluid (mSOF) supplemented with follicle stimulating hormone (FSH), luteinizing hormone (LH), essential and non-essential amino acids at 38.5 ◦ C in a humidified 5% CO 2 , 5% O 2 , and 90% N 2 atmosphere for 72 h. The nuclear maturation rates were evaluated by aceto–orcein staining. Oocytes harvested from follicular and luteal ovaries have a significantly higher matura- tion rates (MI + MII) than the oocytes from anestrual ovaries in the 37 ◦ C group (p < 0.05). However, oocytes harvested from anestrual ovaries transported at 4 ◦ C had the highest mat- uration (MI + MII) rate, and the difference between anestrual and luteal ovary groups was significant (p < 0.05). The oocytes from anestrual ovaries transported at 4 ◦ C have signifi- cantly higher maturation rates than those transported at 37 ◦ C(p < 0.0001). However, the transport temperature (37 or 4 ◦ C) did not significantly affect the maturation (MI + MII) rates of oocytes harvested from the luteal (p = 0.61) and follicular (p = 0.48) stage ovaries. It can be concluded from this study that (1) both transport temperature and transport temperature × estrus cycle stage interaction effected the maturation rates, while estrus cycle stage alone did not, and (2) transporting canine ovaries at 4 ◦ C can improve in vitro maturation rates in oocytes harvested from anestrous ovaries. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Biotechnological studies continue to search for methods to preserve genetic materials for both domestic and endan- gered species. In these studies, one of the most important ∗ Corresponding author. Tel.: +90 212 473 70 70x17264; fax: +90 212 473 72 41. E-mail address: ucirit@istanbul.edu.tr (Ü. Cirit). problems is the transport of ovaries to the laboratory from long distances. Carnivore oocytes could easily be disturbed by in vitro conditions (Songsasen et al., 2002; Rodrigues and Rodrigues, 2003b). Cellular autolysis occurs in ovaries during long transportation periods at body (35–38 ◦ C) tem- peratures (Holt and Picard, 1999). The oocyte proteins, mitogen-activated protein kinase, maturation promoting factor (MPF), and cdc2-kinase are some of the factors allowing oocyte maturation (Fissore et al., 1996; Smitz et al., 2004). The amounts of these species-specific proteins 0378-4320/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.anireprosci.2009.03.004