Macroscopic and microscopic evaluation of Eurasian lynx (Lynx lynx) female tubular reproductive organs in relation to ovarian structures E. Axnér a, * , D. Holm a , D. Gavier-Widén b , A. Söderberg b , A.S. Bergqvist a a Division of Reproduction, Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Health, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden b Department of Pathology and Wildlife Diseases, National Veterinary Institute, Uppsala, Sweden article info Article history: Received 17 November 2014 Received in revised form 23 April 2015 Accepted 3 May 2015 Keywords: Retained luteal body Lynx reproduction Population monitoring Vagina Uterus abstract Although monitoring wild animals in the field is essential for estimations of population size and development, there are pitfalls associated with field monitoring. In addition, some detailed data about reproductive physiology can be difficult to obtain in wild live animals. Studying reproductive organs from the Eurasian lynx killed at hunting or found dead could be used as a valuable addition to other field data. We evaluated reproductive organs from 39 Eurasian lynx females (Lynx lynx) killed in Sweden during the hunting seasons in 2009, 2010, and 2011. According tonotes on ovarian structures, the animals were categorized as being in one of four different reproductive stages: juvenile (n ¼ 10), follicular stage (n ¼ 8), luteal stage (n ¼ 11), and anestrus (n ¼ 10). Corpora lutea were classified as fresh CL from the present season or as luteal bodies from previous cycles. Microscopic evaluations were blindly coded while the outer measurements of the vagina and uterus were taken at the time of organ retrieval. The width of the endometrium, myometrium, outer width of the uterine horns, and the diameter of the vagina differed significantly with the reproductive stage (P < 0.001) and were largest in the follicular and luteal phases. The number of endometrial glands evaluated blindly coded on a subjective scale was significantly asso- ciated with the reproductive stage (P < 0.0001) and was significantly higher in the luteal phase than that in any other reproductive stages (P < 0.05). Cornification of the vaginal epithelium was only observed in females in the follicular stage or in females with signs of a recent ovulation. In conclusion, both macroscopic and histologic measurements are useful for a correct classification of the reproductive stage when evaluating reproductive organs in the Eurasian lynx killed during the hunting season. Routine evaluation of reproductive organs has a potential to be a useful additional tool to field studies of live lynx to monitor their reproduction. Ó 2015 Elsevier Inc. All rights reserved. 1. Introduction New methods for monitoring the reproduction of wild animal species would increase the accuracy in models for population growth and would enhance the possibilities to detect early changes in a species reproductive pattern caused by, for example, environmental pollution or climate change. The Eurasian lynx in Scandinavia is closely moni- tored in the field on a yearly basis, which yields useful and important data about their population [1,2], which are the bases for decisions about management of the population such as determining the annual quota for control hunting. However, there are limitations in field monitoring of live animals. Snow conditions can, for example, affect the * Corresponding author. Tel.: þ46(0)18672181; fax: þ46(0)18673545. E-mail address: Eva.Axner@slu.se (E. Axnér). Contents lists available at ScienceDirect Theriogenology journal homepage: www.theriojournal.com 0093-691X/$ – see front matter Ó 2015 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.theriogenology.2015.05.002 Theriogenology xxx (2015) 1–6