Fig. 3

Exo-erythrocytic stages of Haemoproteus parasites: meronts (a, b) and megalomeronts (c–h). Small mature meront of Haemoproteus palumbis in lungs of a naturally infected nestling of the English wood-pigeon Columba palumbis (a). Group of maturing meronts of Haemoproteus attenuatus in lungs of a naturally infected European robin Erythacus rubecula (note numerous irregular-shaped cytomeres with developing merozoites, b). Numerous developing megalomeronts of Haemoproteus passeris in a section of liver in a naturally infected House sparrow Passer domesticus (note that megalomeronts tend to group, and each megalomeront is covered by a wall and contains several cytomeres, c). A maturing megalomeront of H. passeris (the same preparation as in c; note that the parasite is covered by a thick wall and contains seven well-defined cytomeres, which are covered by a thin membrane and contain numerous irregularly shaped subcytomeres with developing merozoites, d). Two maturing cytomeres of H. passeris (the same preparation as in c; note that the cytomeres separate from each other before maturation, and nuclei locate on the edge of subcytomeres, e). Mature oval megalomeront of Haemoproteus mansoni (syn. Haemoproteus meleagridis) in the section of the pectoral muscle of a turkey Meleagris gallopavo (note that megalomeront is surrounded by thick wall and is overfilled with roundish merozoites; the muscle fibres surrounding the parasite are swollen and pale-stained, f). Rupturing mature roundish megalomeront of H. mansoni (the same preparation as in f; note the swollen tissue surrounding the parasite, g). Mature lobular-shape megalomeront of H. mansoni (the same preparation as in f; note irregular outline of the parasite, h). Simple long arrows meronts, simple wide long arrows megalomeronts, triangle long arrows parasite nuclei, triangle wide long arrows cytomeres, simple wide short arrows subcytomeres, simple short arrows megalomeront wall. Scale bars 10 μm (a, b, e), 50 μm (c, d, f–h)