ULTRASTRUCTURE OF THE COLORLESS FLAGELLATE HYPERAMOEBA-FLAGELLATA WITH SPECIAL REFERENCE TO THE FLAGELLAR APPARATUS

Hyperamoeba flagellata is a fresh-water protist of uncertain taxonomic position. It exists in three living forms: as an amoeba, a flagellate and a cyst, The ultrastructure of the flagellated stage of H. flagell ata is investigated here by TEM for the first time, Special attention was paid to the structure of the flagellar apparatus. There is one lon g smooth flagellum only which is directed anteriorly, It emerges from the flagellar basal body (kinetosome) located at the apical end of the cell. Two cones of microtubules extend from the flagellar base toward s the nucleus. The outer cone originates from the lateral side of the flagellar kinetosome, while the inner cone arises from an MTOC associa ted with the flagellar kinetosome by a short fibrillar rootlet. The se cond (barren) kinetosome lies ventrally and is directed to the right s ide of the cell. It has two microtubular rootlets which pass laterally in the same direction, The microtubular cones overlap the anterior en d of the nucleus, A dictyosome lies between the basal bodies and the n ucleus. Mitochondria with tubular cristae have an electron dense core which is orientated in a longitudinal axis. The structure of the flage llated stage of H. flagellata is compared with flagellated cells of pr otostelids and cercomonads. It is proposed that this organism may repr esent a link between protostelids and cercomonads.