Anatomical variations in the cerebral arterial circle of the Saimaa (Pusa hispida saimensis) and Baltic ringed seals (Pusa hispida botnica)

• Published in: The Anatomical Record
• Main Authors: Laakkonen, Juha, Nihtilä, Heini Vivika, Jernvall, Jukka
• Other Authors: Veterinary Biosciences, Veterinary Anatomy and Developmental Biology, Departments of Faculty of Veterinary Medicine, Jukka Jernvall / Principal Investigator, Institute of Biotechnology
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley/Blackwell 2023
• Subjects: Aquatic adaptations; Brain vasculature; Casts; Mri; Pinnipeds; 1184 Genetics; developmental biology; physiology; Pusa hispida
• Online Access: http://hdl.handle.net/10138/568021

The intracranial arterial vascularization of the Saimaa ringed seals (Pusa hispida saimensis; Nordquist, 1899) and Baltic ringed seals (Pusa hispida botnica; Gmelin, 1788) disclosed patterns of anatomical architecture comparable to that of other pinniped species. Arterial silicone casts on skull scaffolds, and magnetic resonance imaging (MRI) showed that the besides joining the caudal communicating arteries upon entering the cerebral arterial circle, the bilateral internal carotid arteries bifurcated as laterally oriented rostral choroidal arteries and rostral cerebral arteries. The latter arteries almost immediately gave off the laterally oriented middle cerebral arteries. Numerous individual variations were evident in differences in the exact branching sites of bilateral vessels or the size or number of arterial branches. Two Saimaa ringed seals had only a tiny foramen for the left internal carotid artery to enter the intracranial space, and the intracranial part of this vessel was short. It did not reach the cerebral arterial circle. The intracranial part of the right internal carotid artery is bifurcated and also supplied the left side of the cerebral arterial circle. Both specimens had aplasia of the left rostral cerebral artery. The intracranial arterial arrangement of Saimaa and Baltic ringed seals reflects the arterial architecture of this body region in terrestrial mammals with little evidence for aquatic adaptations or changes related to thermoregulation. Peer reviewed