Abstract:Histology and ultrastructure of the cement apparatus of Capitulum miteila were observed by a light microscope and electron microscope.The result showed that the cement apparatus of Capitulum miteila is consisted of cement gland cell and canal system.The entire apparatus is sheathed in a layer of connective tissue, inside of which fibroblasts can be seen. Gland cell is a unicellular gland.The development of cement gland cell and animal itself is not synchronous. The young cement cells are small, and the shapes of cells and nucleus are round, ovoid . With the development of gland cells, the gland cells and their nucleus enlarge, and their shapes become irregular with polymorphism. The cytoplasm of mature gland cells, the electron density of which is high, is full of a lot of the rough endoplasmic reticulum and free ribosomes, a few mitochondria, but no Golgi apparatus. The cytoplasm contains a wealth of particulate matter and sizes of vacuoles. The formation of the intracellular canal in cement glands is via aggregation and fusion of cytoplasmic vacuoles. The canal system system is divided into four levels depending on location and function: intracellular duct, collection duct, secondary duct, principal duct. The collection canals, secondary canals and principal canals are composed of monolayer epithelial cells. The principal duct is larger than secondary duct and collection duct. The cavity of the principal duct has chitinous layer. Septate junctions connect cement gland cells with wall cells of the collector canal. The wall epithelial cells of canals are also connected by septate junctions. This structure ensures the tightness of the canal system.