包囊游仆虫包囊形成和解脱过程中纤毛器的分化

DIFFERENTIATION OF CILIATURE DURING ENCYSTMENT AND EXCYSTMENT IN EUPLOTES ENCYSTICUS

包囊游仆虫(Euplotes encysticus)形成包囊时,各类纤毛器中的纤毛杆被部分地或全部地吸收,毛基体被保留下来。休眠包囊中,背纤毛器的定位无明显变化,但原腹面纤毛器中的口围带和波动膜、额腹棘毛和横棘毛,以及左、右尾棘毛都按序陷入在细胞质内深处,并相互汇聚在一起。脱包囊时,纤毛结构在原毛基体上再分化,新纤毛器按口围带、横棘毛、额腹棘毛和左、右尾棘毛的顺序从细胞内显露出来。

The processes of encystment and excystment of the hypotrich ciliate Explotes encysticus were investigated using living organisms, protargol staining, and scanning electron microscopy. During encystment of E. encysticus, the ciliary shafts of the cortical ciliatures were re-sorbed in part or in whole, while the kinetosomes were preserved. In the resting cyst, the dorsal ciliatures remained more or less at their original positions on the cell surface, but the-adoral zone of membranelles (AZM) and the undulating membrane (UM), the fronto-ventral cirri (FVC) and the transverse cirri (TC), the left caudal cirri (LCC) and the right caudal cirri (RCC), ihvaginated successively into the cytoplasm, and converged to each other. During excystment, the mid-dorsal region was the first to escape from the dorsal ostiole, the anterior was the last to free from the cyst wall. The ciliatures under went a process of redif-ferentiation during which the new ciliary shafts developed on the old kinetosomes. As a result, the newly developing AZM, TC, FVC, LCC and RCC, emerged gradually from the cytoplasm.Additionally, the influence of temperature to the encystment, and the effect of the con-tractile vacuole on the excystment, were analysed.