Himmelhoch, S., Section of Biological Ultrastructure, Weizmann Institute Rehovot, Israel
Cohn, E., Division of Nematology, The Volcani Center Beit Dagan, Israel
Mordechai, M., Division of Nematology, The Volcani Center Beit Dagan, Israel
Zuckerman, B.M., Laboratory of Experimental Biology University of Massachusetts, East Wareham, Massachusetts, United States

Electron microscope studies of citrus roots infected with Tylenchulus semipenetrans showed two distinctive symptoms associated with pathogenesis. First was the presence of paracrystalline arrays within plastids. Second was the formation of enlarged, lobed nuclei. These Tylenchulus induced changes are discussed in relation to host reactions to endoparasitism by other plant nematodes. © 1979, Brill. All rights reserved.