Skin of the Baikal Seal (Pusa Sibirica, Phocidae): Norm and Pathology

The study examined the skin of 12 Baikal seals, identifying both normal and pathological features. Normal skin showed a folded epidermis, hyperkeratosis, and distinct collagen fiber layers, with adaptations for hydrodynamic, thermoregulatory, and sun-protective functions. Pathological findings included two main complexes: koilocytosis with subepidermal inflammation and lymphocyte exocytosis, and subepidermal blister formation with neutrophilic infiltration. These pathologies may be linked to global warming and changes in Lake Baikal's ice regime, potentially triggering immune inflammatory processes, and the role of an unknown viral pathogen causing koilocytosis is also considered.