[Light- and electron-microscopical study of Pelomyxa stagnalis Sp. n. (Archamoebae, Pelobiontida)]

The structure of a new pelomyxa species was investigated with the use of light- and electron-microscope technique. Motile individuals reach 800 microm in length. There is a thin layer of amorphous glycocalix on the cell surface. Many non-motile flagellae are found mainly in the uroidal zone. The axoneme has a non-stable set of microtubules. There are no any special elements in the transition zone. A short kinetosome is about 150 nm long. A bundle of 15-20 microtubules starts from the one side of kinetosome and pass below the cell surface. Structure vacuoles are one of the main cytoplasm components of Pelomyxa stagnalis. Glycogen bodies are surrounded with flattened reticulum cisterns often containing electron-dense material. Two morphological distinct species if prokaryote endobionts were found in the cells of P. stagnalis. The number of nuclei in the cells of P. stagnalis reaches 50 or more. The nuclei are rounded by a two-layer envelope including a multilaminar layer and outer layer, which is formed by small vesicles often containing electron-dense material. One nucleolus is situated at the center of a nucleus. In the nuclei, often in connection with the nucleolus, there are bodies formed by electron-dense threads.