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Abstract Full Text

Systematization, description, and territory of the middle cerebral artery in brain surface of the turtle (Trachemys scripta elegans).

Abstract

The objective of this study is to describe and systematize the middle cerebral artery at the brain surface of the turtle (Trachemys scripta elegans), determining a standard model of irrigation and the main ramifications and territory, in this species. 30 turtles received pre-anesthetic medication of ketamine (80 mg/kg) and midazolam (2 mg/kg) followed by euthanasia with a sodium thiopental (100 mg/kg) overdose. The aortic arches were cannulated through the single ventricle, the cranial cava veins were incised and the vascular system washed with saline solution and heparin, and then filled with latex. Pieces remained immersed in running water and a bone window was opened in the cranial vault. Samples were fixed with formaldehyde and each brain with a spinal cord segment was removed from the cranial vault, the duramater was removed and the arteries dissected. Results were recorded and it was observed that the middle cerebral artery, collateral branch of the rostral branch of the internal carotid artery, varied between one to three components. These vessels anastomosed, originating a net that was projected from the base of the brain reaching the convex surface of the olfactory bulb. Their lateral ramifications formed the convex hemispheric arteries, which ascended to the convex surface of the cerebral hemisphere and reached, caudally, the proximities of the caudal pole, anastomosing with the occipital hemispheric branches of the caudal cerebral artery and, dorsally, anastomosed with the caudal medial hemispheric branches of the caudal inter-hemispheric artery. Rostrally, its terminal branches, dorsal and ventral, formed a vascular ring around the coronal sulcus, which separated the cerebral hemisphere from the sessile olfactory bulb together with the rostral medial hemispheric branches of the rostral inter-hemispheric artery, branch of the rostral cerebral artery. The arteries of the olfactory bulb originated from this ring. The middle cerebral artery in 63.4% of the samples to the right and in 56.7% to the left was double. However, in 33.3% to the right and 20% to the left was triple, whereas in 3.3% to the right and in 23.3% to the left was a single vessel.