| Abstract: | ABSTRACT. The fine structure of the paraxial rod of Phytomonas davidi and Herpetomonas megaseliae was analyzed in thin sections of Triton X-100-extracted, tannic acid-glutaraldehyde-fixed cells and in replicas of quick-frozen, freeze-fractured, deeply etched and rotary shadowed cells. The paraxial rod is formed by a complex array of filaments. Two regions, designated as proximal and distal, are formed by two and at least 11 plates, respectively, composed of an association of 25-nm and 7.0-nm-thick filaments which are oriented at an angle of-50° in relation to the major axis of the axoneme. The intermediate region is less dense and is formed by thin filaments. Short single and Y-shaped filaments connect the proximal plate to doublets numbers 4 and 7 of the axoneme. Based on the images obtained in stereopairs as well as in photographs obtained before and after inclination of the specimen, a three-dimensional model of the paraxial rod is proposed. |
