Electron Microscopic Characterization of Insect Hemocytes
The fine structure of insect hemocytes has been the subject of very few investigations. In particular, the hemocytes of Lepidoptera have received almost no attention. The study presented here was carried out on the armyworm, Pseudaletia unipuncta. Hemocytes of the larva were fixed 2 to 4 days after molt to the sixth instar and studied in ultrathin sections.Microplasmatocytes (Fig. 1) were the most important phagocytes of army-worm hemolymph. They were relatively small, spherical cells with a small, round or lobed nucleus. Distensions of the perinuclear cisterna (p) were frequent and sometimes continuous with the rough endoplasmic reticulum (e). The latter formed greatly distended cisternae which almost filled the whole cytoplasm. The cisternae contained an amorphous material which appeared to be condensed in certain sacs (at e). Mitochondria (m) were rare, and they had tubular cristae. Up to four Golgi complexes (g) were identified in a microplasmatocyte section. Structured granules (sg) were specific for this cell type. Microfibrils (f) traversed the whole cytoplasm but were most frequent around the nucleus (N) and under the cell membrane.