S. A. Karpov
Laboratory of Lower Organism Biology, Institute of Biology of
Inland Waters of the Academy of Sciences of the USSR, Borok, Russia
Tsitologiya 24: 400-404 (1982) [in Russian]
The fine structure of choanoflagellate Monosiga ovata was studied with special reference to the basal flagellar apparatus and ingestion of bacteria. The cell is covered by a very thin envelope which is visible only after few methods of fixation. The general cell morphology is similar to that of other choanoflagellates. The flagellar root system consists of radiating microtubules originating from the electron-dense ring around the base of kinetosome. The flagellar transition zone is organized in type II, according to Pitelka (1974), but the central tubules of the axoneme are associated with the transverse plate by a central filament. There are microfilaments in the tentacles of the collar. The electron microscopic study of the capture and ingestion of bacteria has demonstrated a relationship between the engulfing pseudopodium and the adjacent collar tentacles.