The Arterial Circle of the Brain, Its Branches and Connections in Selected Representatives of the Antilopinae Hieronim Fra˛ckowiak, Dariusz De R bi  nski, Marcin Komosa, and Maciej Zdun* Department of Anatomy of Animals, Poznan University of Life Sciences, PL-60–625 Pozna n, Poland ABSTRACT The arterial circle of the brain, that is, the circle of Willis, and its branches in ruminants have been chiefly described in farm animals and only in selected wild species. In view of the deficit of informa- tion about this vascular region in numerous other spe- cies of the Ruminantia, the arteries of the encephalic base were analyzed in five antelope species represent- ing different genera of the Bovidae, Antilopinae. Speci- mens of the following species were examined: springbuck (Antidorcas marsupialis), blackbuck (Anti- lope cervicapra), dik-dik (Madoqua kirkii), saiga (Saiga tatarica), and oribi (Ourebia ourebi). Post-autopsy material received from domestic zoological gardens was used to inject the bilateral common carotid arteries with a stained acetone solution of vinyl superchloride. When the material was polymerized, the specimens were macerated enzymatically. The process resulted in casts of arteries of the head and encephalic base on a skeletal scaffold. The investigations revealed that the bilateral components of the arterial circle of the brain, that is, the rostral cerebral artery and caudal commu- nicating artery, arose from the division of the intracra- nial segment of the internal carotid artery, which emerges from the rostral epidural rete mirabile. The extracranial segment of the internal carotid artery was obliterated. In consequence of this process, the blood reaches the brain chiefly from the maxillary artery. The research proved that the arteries of the encephalic base in the Antilopinae are most similar to the vessels described in antelopes of Tragelaphus, Taurotragus, and Boselaphus genera and small domestic ruminants. However, they are different from the arterial pattern of the encephalic base in bovines and other species classified as the Bovini. J. Morphol. 276:766–771, 2015. V C 2015 Wiley Periodicals, Inc. KEY WORDS: cerebral arteries; circle of Willis; brain base arteries; antelopes; ruminants INTRODUCTION In ruminants, the arterial circle of the brain, that is, the circle of Willis, and its branches have mainly been described in farm animals and only in a selected number of wild species including buf- falo (Rao et al., 1968); roe deer (Godynicki and Wiland, 1970, 1971; Jablo  nski, 2005); one-humped camels (Ocal et al., 1998); other camelids (Kieltyka-Kurc et al., 2014); yaks (Ding et al., 2007; Wang et al., 2012a,b); European bisons (We R grzyn et al., 1983); giraffes (Fra˛ckowiak and Jakubowski, 2008); fallow deer (Brudnicki, 2011); species of the Bovini (Zdun et al., 2013), and ante- lopes of Tragelaphus, Taurotragus, and Boselaphus genera (Fra˛ckowiak et al., 2014). The interest in this topic is proved by further publications describ- ing this vascular region in humans (Cieslik and Ciesla, 2005; Alstruey et al., 2007) and in animals (Ding et al., 2007; Dorr et al., 2007; Caldwell et al., 2011). In view of the deficit of information about this vascular region in numerous other species of the Ruminantia (McKenna and Bell, 1997), these arteries were analyzed in this study in several species of the Antilopinae, including the critically endangered Saiga (Saiga tatarica), which is on the IUCN Red List of Threatened Species, the threat- ened blackbuck (Antilope cervicapra), and the dik- dik (Madoqua kirkii), as well as the oribi (Ourebia ourebi), which are of least concern. This study not only broadened our knowledge of about the arteries of the encephalic base in the Ruminantia, but also reports about general biolog- ical facts, which may be useful in further discus- sion, for example, on positioning the species in taxonomy. Bugge (1974, 1978) showed examples of considerable similarity between selected traits of the arterial system in the head and encephalon of the species of different orders of contemporary mammals and their position in zoological taxon- omy. Godynicki (1972) and Fra˛ckowiak (2003) found a similar regularity in the Artiodactyla. The universality of this regularity was also proved by the publications by Kielan-Jaworowska et al. (1986), Wible (1987), and Rougier et al. (1992), who used the characteristics of the cranial arterial *Correspondence to: Maciej Zdun; Department of Anatomy of Ani- mals, Poznan University of Life Sciences, Wojska Polskiego 71c, PL-60–625 Pozna n, Poland. E-mail: maciej.zdun@up.poznan.pl Received 17 July 2014; Revised 19 January 2015; Accepted 25 January 2015. Published online 18 February 2015 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/jmor.20377 V C 2015 WILEY PERIODICALS, INC. JOURNAL OF MORPHOLOGY 276:766–771 (2015)