Repeated hypoxic events are reported in various brain pathologies. Mammal brain is highly vulnerable to hypoxia, because brain functions require high oxygen and energy demands. Marine mammals, such as pinnipeds, were naturally selected to cope with daily repeated hypoxic events during foraging dives, when human brain can only cope with minor repeated hypoxia. How do pinnipeds cope with repeated severe hypoxic events at the blood-brain interface? We performed a comparative physiological approach using for model the Southern Elephant Seal (SES), which is the most extreme diver of all seals and being exposed to severe peripheral hypoxia. Immunolabelling of various blood-brain interface markers (endothelium, astrocytes, neurons) were performed on brain cortical slices from freshly dead post-weaning pups (n=4) and reproductive adults (n=5) collected at Kerguelen Island. Immunolabelling were visualised using confocal microscope and images were analysed using ImageJ. Cerebral vascularisation exhibits significant differences between pups and adults: 1) in the grey matter, the vascular volume fraction was around 62% higher in adults than in pups; 2) the vessels were significantly more ramified and tortuous in adults (e.g. 6% more tortuous in the white matter); 3) some large blood vessels exhibited abnormalities in adults suggesting blood-brain interface dysfunctions. Interestingly, adult SES vessels share similar phenotypes to pathological cerebral-blood vessels described in human neurodegenerative diseases. Then, abnormal vessel-morphologies raise the question of the potential pathological situation for adult SES. To study blood-flow velocity in brain-vessels and premature aging in SES, biomechanical fluid modelling, additional staining for neurodegenerative landmarks and blood-biomarkers are currently performed.