Collateral Arteries of the Aortic Arch in Mongolian Gerbil (Meriones unguiculatus)

Abstract

Background: Gerbils (Meriones unguiculatus) are rodents belonging to the Muridae family. Recently, breeding of this species as pets has increased significantly. Animal models are being investigated to study diseases related to the human aortic arch. Despite the importance of the aortic arch in maintaining homeostasis, there is limited data available regarding its morphology in gerbils. This study was performed with the objective of describing the collateral branches of the aortic arch in this animal to establish a standard model and thus contribute to future research on cardiovascular diseases in humans.Materials, Methods & Results: This study used 20 male specimens from previous studies that were frozen and stored at the Laboratory of Veterinary Anatomy of the Federal Rural University of the Semi-Arid Region. After thawing the animals, the thoracic cavity was opened for aortic cannulation. The vascular system was washed using saline solution and Neoprene latex stained with red pigment was injected. Subsequently, the animals were fixed in 10% formaldehyde and were dissected and analyzed 72 h later. The arrangement of the collateral branches of the aortic arch in gerbils was analyzed in all animals. The brachiocephalic trunk, the left common carotid, and the left subclavian artery were observed to originate as collateral branches. The brachiocephalic trunk bifurcated into the right common carotid and the right subclavian arteries. The right and the left subclavian arteries branched into the vertebral artery, the internal thoracic artery, the superficial cervical artery, the costocervical trunk, and the axillary artery.Discussion: Several studies reported in the literature describe the collateral branches of the aortic arch in domestic and wild mammalian species. These studies examined the main arteries that originate directly from the aortic arch and their respective branches, and classified the different anatomical variants of the aortic arch in each species. Three different arrangements have been commonly described. The first type corresponds only to the brachiocephalic artery originating from the aortic arch. The right and the left common carotid arteries and the right and the left subclavian arteries originate from this brachiocephalic artery. This type has already been described in the laboratory rat, catingueiro-deer, cattle, and horses. The second type is characterized by the presence of 2 arteries - the brachiocephalic trunk and the left subclavian artery. The right and the left common carotid arteries and the right subclavian artery originate from the brachiocephalic trunk. This arrangement has been reported in most species already studied such as rodents including the paca, chinchilla, guinea pig, mocó, nutria and the preá. The third type of vascular arrangement is observed in the gerbil. In this species, 3 collateral arteries originate from the aortic arch (the brachiocephalic trunk, the left common carotid, and the left subclavian artery). The right common carotid and the right subclavian artery originate from the brachiocephalic trunk. This vascular model has been described in the manatee, in humans, mice, sauim, and the monkey-nail. Thus, we concluded that the branching pattern of the aortic arch of the gerbil was characterized by the brachiocephalic trunk, the left common carotid, and the left subclavian artery, as has been described in mice, the manatee, monkey-nail, sauim, and humans. Based on these morphological characteristics, gerbils could serve as potential experimental models to study diseases related to the human aortic arch.