Abstract
The fine structure of haemocytes in the freshwater mite Unionicola tetra/uTcatus is described and compared with other species of invertebrates. The present study reveals that the haemocytes consist mainly of two types; agranulocytes and granulocytes. The granulocytes is subdivided into 7-types (I-VD). The granulocytes are more abundant, larger in' size with smaller nuclei and larger amount of granulated cytoplasm. The agranulocytes, one type only, have no role in phagocytosis, while the granulocytes have an important role in phagocytic defense reactions. The phagocytic: process occ:urs by formation of pseudopodia and phagosomes.