SOME ULTRASTRUCTURAL STUDIES ON RESTING CYSTS AND THEIR ORGANELLES IN Paraurostyla weissei (Ciliophora,Hypotrichida)

An electron microscopic study of resting cysts and their organelles in Paraurostyla weissei has revealed that:⑴The cyst wall is composed of four layers named from outside to inside:ectocyst,mesocyst,endocyst,and granular layer.The granular layer is delimited by the cell pellicle.Both the layer and pellicle contain a few vesicles.⑵Tubular mitochondria are apparent contrast to their surrounding cytoplasm.The mitochondria are mostly converged to each other,except that a few of those separately scattered in cytoplasm.⑶There are a lot of autophagic vacuoles which contain digested ,undigested mitochondria and other organelles,and,these vacuoles undergo digestivelly cyclic changes.⑷The well developed endomembrane system are widely dispersed over cytoplasmic area.It is supposed from these observations that:⑴The above vesicle are the structure of resting cell,which would be used in exchange for the matter between the granular layer and cytoplasm on both sides of the pellicle.⑵The digestion within autophagic vacuoles might be the main way to supply material and energy in the resting cell.And,as an important source,the membranous structures,which exist in the cytoplasm,would be used to form the membrane of autophagic vacuoles.