Light microscopic study of granulocytes of Pygoscelid penguins (Pygoscelis adeliae) of Antarctica

Morphologic features of heterophils, eosinophils, and basophils of wild adult Pygoscelid penguins (Pygoscelis adeliae; 1 male, 4 females) of Antarctica were studied. Granulocytes were described on the basis of analysis of stained blood films and of 0.5-micron sections of centrifuged resin-embedded blood. Morphometric analysis of granulocytes included average cell diameter, cell shape, and nuclear configuration as well as the number, size, and shape of intracytoplasmic granules. Large round heterophils were the most prevalent granulocyte and possessed numerous rod- and spindle-shaped granules and a polymorphous nucleus. The second most prevalent granulocyte was the eosinophil. These eosinophils contained a bilobed nucleus and an average of 29.52 homogeneous granules/cell. The smallest and least encountered granulocyte was the basophil. Basophils possessed a single eccentric nucleus surrounded by round metachromatic granules (12.20 granules/cell) of varying size.