阔口尖毛虫形成包囊期间细胞超微结构的观察

阔口尖毛虫形成囊期间，细胞质内出现条带状或管产产的内质网和由不同大小的囊泡组成的包囊壁前体。并且，前体的产生与内质网有关；细胞质内发生自噬泡消化现象，这是细胞将原有结构和能量进行贮存，利用的一种重要形式；大核向细胞质突出形成阿米巴形结构，这与大核向细胞质排出部分核物质有关。

OBSERVATIONS ON CELLULAR ULTRASTRUCTURE DURING ENCYSTMENT OF OXYTRICHA PLATYSTOMA

The relationship between organelles,the formation of cyst wall precursors,and the developing mechanism of cortical cytoplasm during encystment in ciliates were studied with the following observations:(1)During encystment of Oxytricha platystoma, large quantities of membranous strctures(layered,stripe shaped and/or tubular shaped)and vesicles of various sizes appear within cortical cytoplasm.They migrate towards the pellicle,accompanied with cyst wall and many sub pellicle vesicles.Autophagic vacuoles surround tubular shaped structures etc.and perform digestive processes.Mitochondria near these vacuoles possess typical tubular cristae.Granular contents and paraglycogen granules also accumulate gradually.Macronuclear envelop and partial matrix protrude into the cytoplasm,forming pseudopodia shaped strctures.Some macronuclear chromatin aggregate into ring shape,with dense,tiny particles in it.(2)After the formation of resting cysts,the cyst wall is four layered structure.There are many differentiated electron dense spherical bodies,highly condensed mitochondria,microtubular filaments,and dense particles in the cytoplasm of the cyst.Outside these spherical bodied,there are many paraglycogen particles. Form the above observation,it can be derived as follows:(1)The stripeshaped and/or tubular shaped structures might be the endoplasmic reticulum formed by cytoplasmic differentiation during Oxytricha encystment.Besides,the cytoplasmic vesicles might be the cyst wall forming precursors,and endoplasmic reticulum might play some role in the formation of the precursors.(2)Digestion within the autophagic vacuoles might be an inevitable step in the progress related to cytoplasmic de differentiation,i.e.,an important phase of storing raw materials and energy from cell s original structures.(3)Pseudopodia shaped structures protrude from macronucleus into cytoplasm might be related to the excretion of nuclear substances into the cytoplasm.