The surface of the egg of a parasitic insect. II. The ultrastructure of the particulate coat on the egg of Nemeritis

Abstract

The particulate secretion from the calyx cells of Nemeritis , which is thought to confer protection on the parasitoid, has been examined in detail ultrastructurally, using sectioned and negatively-stained material and enzyme-digest techniques. These membrane-bounded particles are produced in large numbers within the nuclei of the calyx cells and are found in vast numbers in the lumen of the calyx. Only a few have been seen in the cytoplasm of the cells, and it may be inferred that they pass quickly through the cells. They appear in the microvilli of the luminal surface, and are released when the tips of microvilli enclosing particles become pinched off. As shown in the preceding paper, they become attached to the outer layer of the chorion of eggs passing through the calyx. The first signs of particles appear to be the presence of empty membranes found in the nuclei of 17-day-old individuals, and their development has been traced through to the adult stage of the parasitoid. The unique nature of the particulate secretion is discussed.