Intracellular digestive process of food in a fresh water ciliate Stylonychia mytilus (Protozoa, Ciliophora, Hypotrichida)

摘要

The whole intracellular digestive process of the hypotrichous ciliate Stylonychia mytilus was observed by immunofluorescence microscopy, transmission electron microscopy and electronmicroscopical enzyme cytochemical techniques. Initially, when food entered the digestive system, food was surrounded by two membranous structures, but very soon the outer layer was digested and then vanished. Thereafter, the digestive process could be divided into two types. In the first, food was digested directly in the digestive channel system as Kaul et al. (1982) and Dass et al. had reported. In the second food gradually penetrated into the cytoplasm, and was finally surrounded by cytoplasm and a single-layered membraneous vacuolar structure was formed. During this process at the edge of the cytoplasm, many vesicles which contained substances including acid phosphatase were visible. When the vesicles fused with food, hydrolases such as acid phosphatase were released. The pellicle of food gradually disintegrated, and became smaller. Finally, the digested nutrients were released into the digestive system. These vacuoles were named as “secondary food vacuoles”. These two digestive processes occur in association with the digestive channel structure organelle of Stylonychia mytilus . It is uncertain which process is more advanced, or that these processes only occur in Stylonychia mytilus [ Acta Zoologica Sinica 54(3): 510–516, 2008].