钩刺目纤毛虫──多核前裂虫的超微结构研究

OBSERVATIONS ON THE ULTRASTRUCTURE OF ENCHELYDIUM POLYNUCLEATUM (CILIOPHORA:HAPTORIDA)

对钩刺目一土壤纤毛虫──多核前裂虫的超微结构做了透射电镜观察。该种表现了与其他钩刺目种类相似的特征，包括体表分布的粘丝泡以及扁平的表膜泡。其主要细胞结构特征为：1）一层连续的膜层状内质网将虫体细胞质分成内外两部分；2）线粒体仅密集于内层细胞质；3）平行于唇突表面的特殊的前列横微管束系由胞口发出，沿唇突表层向体后发出并纵行环绕于胞咽外侧；此前列横微管束明显地呈片层状构造；4）射出体包括位于口区的两种长短不同的毒丝泡和遍布于体区表膜下的粘丝泡。本研究结果支持该种（类）作为一较低级的独立阶元而列于钩刺目内。

The ultrastructure of a large soil ciliate, Enchelydium pohaucleatum Foissner,1984 (Protozoa, Ciliophora, Haptorida) has been observed using transmission electron microscopy. Our observations support the previous descriptions about this species and the results are generally similar to those obtained in many other haptorids (Lacrymaria,Litonotus, Homalozoon etc),e. g. The existence of two kinds of toxicysts and one type of mucocyst, as well as the cortex with membrane-bounded flat alveoli.Ultrastructural characteristics of E. polynucleatum may include 1) a large cistern of the endoplasmic reticulum separating the inner and outer portion of the cytoplasm; 2)mitochondria distributed only within the inner portion (the endoplasm) ; 3) strongly developed transverse microtubule ribbon turning to the rim of the oral bulge and then extending anteriorly along the wall of cytostome, where they plunge inwards to support the cytopharynx, and 4) two kinds of argentophic toxicysts (the long type and the short one), which are restricted to the oral region and whose structure is similar to that of other haptorids, while the mucocysts being close-set and distributed only in somatic region immediately beneath the pellicle.We suggest that this organism, as a untypical form of haptorida (with primitive dorsal brushes but without dikinetid circum oral kineties), should be placed in a 'lower' position in the order.