AN ELECTRON MICROSCOPE STUDY OF THE CYTOLOGY OF THE PROTOZOAN EUPLOTES PATELLA

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Abstract
Structurally the "sensory bristles" in E. patella are typical cilia, but no ciliary rootlets connect their bases. The "neuromotor fibrils" are composed of filaments 21 m[mu] in diameter. At the point of junction of the filaments with the peripheral ciliary fibrils, is a granular structure 65 to 90 m[mu] in diameter with dense central and peripheral zones separated by a less dense layer. A system of subpellicular fibrils is described, but the external fibrillar system described by others could not be found. The motorium is shown to be a mass of intertwining rootlet filaments. The micronucleus consists of spongy, dense material in less dense material, and is surrounded by a double-layered membrane. The double-layered macronuclear membrane contains annuli whose outside diameter is 70 m[mu]; the macronuclear bodies are sometimes closely applied to the membrane. In the macronuclear reorganization bands, the solution plane is a fine network, while the reconstruction plane is devoid of structure at the level of resolution observed. The mitochondria are composed of tubules, usually embedded in a surrounding material of lower density. Microbodies whose diameters are 250 to 350 m[mu] are frequently observed in close association with mitochondrial surfaces. The food vacuoles, contractile vacuoles, and ciliary vacuoles are bounded by single-layered membranes. In food vacuoles, the bacteria, either singly or in small groups, are surrounded by membranes. Cytoplasmic rods localized in the oral region, and cytoplasmic granules dispersed at random, are described. No typical ergastoplasm, endo-plasmic reticulum, or Golgi material was observed.