PLASMA-MEMBRANE SPECIALIZATIONS IN RESTING, STIMULATED AND PHAGOCYTOSING ARTHROPOD (LIMULUS-POLYPHEMUS, GROMPHADORHINA-PORTENTOSA AND BLATTELLA-GERMANICA) IMMUNOCYTES - STRUCTURAL AND FUNCTIONAL ANALOGIES WITHTHOSE OF VERTEBRATE MACROPHAGES AND NEUTROPHILS

Using indirect immunofluorescence and scanning electron microscope tec hniques, we have shown that the plasma membrane specializations, such as pseudopods, filopods, lamellipods, and zeiotic blebs occur in activ ated and/or phagocytosing arthropod (Limulus polyphemus, Gromphadorhin a portentosa, and Blattella germanica) immunocytes (hemocytes), as the y do in challenged vertebrate neutrophils and macrophages. All four sp ecializations may also be caused by some of the chemicals in the prepa rative media, which suggests that arthropod immunocytes, like the vert ebrate neutrophils and macrophages, have evolved as highly reactive ce lls that are sensitive to chemical and/or biological foreign agonists/ antigens. These attributes are necessary for the effectiveness of a ce llular defense mechanism. The plasma membrane specializations perform the same functions in arthropod immunocytes as reported for those of v ertebrates. For example, pseudopods and lamellipods are needed for spr eading and locomotion and filopodia for cell adhesion and crawling. Be cause they are formed as a result of similar reactions to foreign anti gens, as in vertebrate cells, it is suggested that similar terminologi es be consistently used for them in arthropods.