Some Ultrastructural Characteristics of the Polysaprobic Ciliate Trimyema compressum

The cortex of Trimyema compressum is characterized by the presence of a well-developed alveolar layer, single kinetosomes with a long kinetodesmal fibril, a postciliary ribbon of 10-11 microtubules, a transverse ribbon of 4-6 microtubules, by the presence of mucocysts, and the lack of an ecto-endoplasmic microfibrillar layer. The vestibular ciliature is carried by numerous short segments of kineties which are the anterior parts of the somatic kineties. The vestibule is limited by microtubular fibers which are probably transverse microtubules. As in the other species of polysaprobic ciliates (Metopus), the mitochondria lack microvilli and have a dense matrix. They are gathered in groups associated with the ergastoplasm. There are no symbiotic bacteria.