Seasonally dependent morphological variations of circulating hemocytes in Helix pomatia
Total number and types of hemocytes were analysed in hemolymph of Roman snail (Helix pomatia L.). Significant differences in the number and types of hemocytes during the season at different locations were identified. The average number of hemocytes ranged from 154 to 288 per 10 μL of hemolymph. The highest number of hemocytes was recorded in snails at higher altitudes. Significant intergroup differences between all sites were identified. The most numerous hemocytes were granulocytes, followed by agranulocytes, while hyalinocytes were the least common in the post-hibernation period. Post hoc analysis showed certain intragroup differences for most locations except for comparison between wet habitat and habitats with anthropogenic influence, and between wet habitats and urban place with wet vegetation. A large number of transformed hemocytes in the encapsulated phase were identified in snail hemolymph infected with flat worms. Our results represent the first record of data for the number of hemocytes in molluscs and the first data for hemocytes of Helix pomatia. Further investigations and development of a uniform classification of hemocytes and their role in the immune response would be necessary in the future.