Abstract
Studying the blood cell morphology of marine mammals provides an opportunity to elucidate the physiological mechanisms of adaptive changes associated with the aquatic habitat that occur at the cellular level, as well as adaptations to changing environmental conditions and under various physiological and pathological processes. The Baikal seal [Pusa sibirica (family Phocidae)] is endemic to the freshwater Lake Baikal, but comprehensive hematology data are not available. We studied the morphological features of blood cells of twelve clinically normal, adult Baikal seals (n = 6 males, n = 6 females) from two oceanariums under professional care for eight years. The morphology of mature and immature erythrocytes and inclusions are described. The blood of Baikal seals is characterized by the presence of erythrocytes with a size of 8.2 ± 0.6 µm; Howell-Jolly bodies were rarely observed, the number of reticulocytes ranged from 4.1 to 93.1 × 10(9)/L, and nucleated erythrocytes were absent. The morphological features of neutrophils, eosinophils, basophils, and platelets were described. Inter-individual and sex differences in the counts of basophils, platelets, red blood cells, and levels of hemoglobin, the mean corpuscular volume, and the mean corpuscular hemoglobin concentration were statistically observed. The results could be useful for Baikal seal veterinary care, immune response research, and comparative studies with other pinnipeds.