Observations by Scanning Electron Microscopy of Surface Events during Encystment and Excystment in Gastrostyla steinii (Cliophora, Hypotrichida)

Abstract

The surface of the protozoan Gastrostyla steinii undergoes profound morphological changes during the encystment and excystment processes. Resorption of the various ciliary structures occurs progressively during differentiation of the free living cell into the resting cyst. In ciliar disassembly, layers of the cyst wall are deposited on the surface of the encysting organism. At excystation, the hatching trophozoite emerges from the protective wall through a cleft after the formation of the ciliary organelles.