Paramoeba

Index | Introduction | Appearance | Ultrastructure | Reproduction and Life History | Similar genera | Classification | Taxonomy and Nomenclature | Cultures | References | Internet resources


REPRODUCTION AND LIFE HISTORY

Paramoeba cells reproduce asexually by binary fission, with mitotic division of the nucleus. Division of the parasome also occurs, either simultaneously with the nucleus or at some time before cytokinesis.


No electron-microscopic observations have been made on nuclear or parasomal division. At the light microscope level, mitotic division is of the "mesomitotic" pattern. The nucleolus and nuclear envelope are no longer visible after prophase. Spindle microtubules extend from discrete poles to the chromosomes. No centrioles or other obvious structures are present at the poles. Cytokinesis normally occurs immediately after the completion of mitosis.
How the parasome divides is unknown; light microscopical observations do not reveal figures that resemble mitosis.
The most accessible report of cell division in Paramoeba is that by Page (1970).

There are no flagellate stages in the life history. Protistologists in the late 19th and early 20th centuries, including Schaudinn, the person who first described Paramoeba, sometimes reported that flagellate stages were present. These early workers usually did not have access to monoprotist cultures. The existence of flagellate cells was refuted by Hollande (1940, 1980), who found that the "zooids" seen by Schaudinn and others were contaminants representing unrelated protistan species.


No sexual reproduction or cysts of any type have been observed.


Paramoeba:   Index | Introduction | Appearance | Ultrastructure | Reproduction and Life History | Similar genera | Classification | Taxonomy and Nomenclature | Cultures | References | Internet resources

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