THE STRUCTURE AND BEHAVIOR OF GYPSY-MOTH (LYMANTRIA-DISPAR) HEMOCYTES

Light and electron microscope observations of gypsy moth larval hemocy tes show seven distinct and readily identifiable types of circulating cells: prohemocytes, granulocytes, coagulocytes, adipohemocytes, plasm atocytes, oenocytoids, and spherulocytes. In addition to these seven, a large, motile, highly refractive cell was observed with the light mi croscope, but little was elucidated about its ontogeny or function. Pl asmatocytes, granulocytes, and coagulocytes constituted the largest po rtion of the hemocyte population. Plasmatocytes were distinguished by their large spindle shape and large dumbbell-shaped nuclei. These cell s were motile and rapidly spread out on a glass microscope slide. Gran ulocytes characteristically contained secretory granules with a microt ubular-filamentous substructure. They also contained vacuoles, microtu bules, and substantial rough endoplasmic reticulum. Both plasmatocytes and granulocytes were phagocytic. The fragile coagulocytes were disti nguished by the dilated perinuclear space, absence of granules, and by ejection of the nucleus from the cell. Spherulocytes contained refrac tive, membrane-bound inclusions with a crystal-like substructure and a central nucleus. Oenocytoids were typically large, with smooth, hyali ne cytoplasm and a tiny eccentric nucleus. These particular cells incr eased in number just before and during ecdysis. Adipohemocytes contain ed numerous lipid globules of different sizes; these cells were partic ularly conspicuous in late instar larvae and pupae. Only the granulocy tes and coagulocytes appeared to be important in coagulation. During t his process the granular-floccular contents of the granulocytes were e xtruded by exocytosis while some cells lysed. Coagulocytes were probab ly the first to lyse. The coagulum was extremely sticky and trapped ot her hemocytes which subsequently lysed. The debris from these cells wa s a component of the coagulum which eventually became melanized. (C) 1 996 Academic Press, Inc.