Euplotes moebiusi f. quadricirratus (Ciliophora, Hypotrichida) I. Die Feinstruktur des Cortex und der argyrophilen Strukturen

Abstract

The fine structure of the cortex and argyrophilic structures of Euplotes moebiusi f. quadricirratus (Kahl 1930-1935) was investigated. (1) The species is redescribed. It differs from Euplotes charon (O.F. Müller 1773) in number of bristle rows and caudal cirri, and in the pattern of the dorsal silverline system. (2) The pellicle consists of a pellicle membrane, which is continuous over the whole cell, and membrane-bounded alveoli. Below the inner alveolar-membrane there are two layers of microtubules. Between two adjacent alveoli there is a triangular interalveolarseptum containing a fibril. These fibrils have a diameter of about 30 nm and consist of a fibro-granular material. They are argyrophil and form the silverline system to be seen with the light microscope. These results were verified by the electronmicroscopic investigation of ultrathin sections from specimens prepared with the wet and the dry silver method. A 3-dimensional drawing shows the positioning of the above structures in the cortex. It is proposed that the cortex of all species of the genus Euplotes is based on the same principle. Many unexplained and incorrect interpreted observations can be explained by means of this concept (Abb. 2). (3) The linkages between the silverline system and the dorsal bristle complex could be elucidated electron-microscopically. The silverline system forms an outer and an inner circular fibril in this region. Both circular fibrils are linked by silverlines and are continous with the silverline system of the body. The outer circular fibril is linked with the secretoric ampulles and consists of an about 130 -160 nm high ring of argyrophilic substance. Accordingly, the heavy argyrophilie of this fibril can be explained by this concentration of argyrophilic substance. The basal bodies of the cilies are linked with the inner circular fibril. A 3-dimensional drawing shows the positioning of the above structures in the cortex (Abb. 3). (4) The alveoli are lacking between the cilies of the cirri and adoral membranelles. Below the pellicle membrane there is a thin, fibro-granular, argyrophilic zone originating from the fibrils of the interalveolarsepti, and linked with definite structures of the basal bodies. Some new features of the basal bodies of the cirri and adoral membranelles are described. The silver is deposited mainly in the surroundings of the axosome. A schematic drawing shows the positioning of the above structures in the cortex (Abb. 4). (5) The epipharyngeal organelles have a weak argyrophilie. Their origin from the egestion vacuoles is shown. (6) The structure and function of the silverline system is discussed. We call attention to the possibility of a morphogenetic and nervous function of the silverline system because the newer results about morphogenesis and ciliary coordination in ciliates are not incompatible with this hypothesis, originally erected by Klein.