Division of Veterinary Anatomy and Developmental Biology, Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
Anat Rec (Hoboken). 2024 Mar;307(3):677-689. doi: 10.1002/ar.25322. Epub 2023 Sep 14.
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.
塞马环斑海豹（Pusa hispida saimensis；Nordquist，1899）和波罗的海环斑海豹（Pusa hispida botnica；Gmelin，1788）的颅内动脉血管化模式与其他鳍足类物种的解剖结构相似。颅骨支架上的动脉硅酮铸型和磁共振成像（MRI）显示，双侧颈内动脉除了在进入大脑动脉环时与尾侧交通动脉相连外，还分叉为侧向的颅脉络膜动脉和额脑动脉。后者几乎立即发出侧向的大脑中动脉。在双侧血管的确切分支部位、动脉分支的大小或数量上存在明显的个体差异。两只塞马环斑海豹只有一个小小的左颈内动脉进入颅内的孔，这条血管的颅内部分很短，没有到达大脑动脉环。右颈内动脉的颅内部分分叉，并供应大脑动脉环的左侧。这两个标本的左侧额脑动脉都发育不全。塞马环斑海豹和波罗的海环斑海豹的颅内动脉排列反映了该身体区域在陆地哺乳动物中的动脉结构，几乎没有水生适应或与体温调节相关的变化的证据。
