The coronary arteries of the Syrian hamster, Mesocricetus auratus (Waterhouse 1839).

Bearing in mind that the Syrian hamster provides an animal model for the study of congenital coronary artery anomalies, we decided to undertake a definition of its normal coronary artery pattern. The sample examined consisted of 1204 specimens. They were studied both histologically and by means of a corrosion-cast technique. The course of the coronary arteries in this species is intramyocardial. The right coronary artery has two principal branches: the right circumflex branch and the dorsal interventricular branch. The conal branch usually originates from the main trunk of the right coronary artery. The main branches of the left coronary artery are the obtuse marginal branch, the left circumflex branch, and usually a dorsal ventricular branch as well. The ventral interventricular branch is often absent. When it is present, it always originates from the left coronary artery and seldom reaches the apex of the heart. The interventricular septum is principally supplied by one, or rarely two, septal arteries arising from the right and/or left coronary arteries. According to the number and origin of these vessels, three septal coronary artery patterns were established; namely, the right, the left, and the right-left septal patterns. In the Syrian hamster, the left septal pattern is the most frequent (70.4%). The right septal pattern occurred in 28.1% of the specimens studied, whereas the right-left septal pattern was only found in 1.5% of them.