Observations On The Oral Organelle, Cytopharynx And Subpellicular Structure Of A Dileptus Sp. By The Electron Microscopy

The oral organelle, cytopharynx and subpellicular structure of a Dileptus sp. wereobserved by the scanning electron microscopy (SEM) and transmission electronmicroscopy (TEM). Main results are as follows:(1) the cytostome is located on theventral of proboscis base, and surrounded by the circumoral kinety which gathertogether into135microtubule fasciculi. When these microtubule fasciculi shrinkage (itsdiameter is about0.4μm), and radial form disk, the cytostome is closed. When thesemicrotubule fasciculi tensile (its diameter is about0.36μm) and invagination to thecytostome, the cytostome is opened. Whether the cytostome closed or opened, thecytostome is always about16μm in diameter, which express these microtubule fasciculishrinkage or tensile is not change the size of the cytostome. It is only related to thesemicrotubule fasciculi whether gag the cytostome, which is determine the cytostomeclosed or opened. There are also many of the microtubule fasciculi which are located onboth sides of the gap on the feeding groove, their functions should have something to dowith proboscis preying for food, the concrete function mechanism is still not clear.(2)The cytopharynx is no bottom of the hoop in shape and about6μm in diameter, andwoven formation by two kinds of fibers which are0.08μm and0.19μm in diameter,respectively.(3) There are two types of toxicysts beneath the pellicle. In the SEM: TypeⅠ toxicysts are two slightly thin clavate, the length is about5μm, the diameter of themiddle section is about0.75μm, and the diameter of the two ends is about0.32μm, thetoxicysts are distributed abundantly between the microtubule fasciculi which are locatedon both sides of the gap on the feeding groove. Type Ⅱ toxicysts are egg and about1.6×0.8μm in size, the toxicysts are distributed abundantly beneath the somatic pelliclewhile rarely the proboscis. Many different of developmental stages two types oftoxicysts can be also seen in the cytoplasm.(4) There is a very flourishing fiber systembeneath the pellicle. The fiber system is woven formation by a fiber which is about0.14μm in diameter, and adheres to the pellicle. Its function is to: bondage and fix someorganelles (eg mitochondria and extrusomes) and other structures in the cytoplasm;maintain cell morphology.(5) Some other structures beneath the pellicle: There are many alveoli beneath the pellicle. Each of the two alveoli forms a bulge to thecytoplasm. The bulge arranges regularly and its diameter is about1.4μm. Beneath thepellicle has a fibril medulla which is constituted by many fiber layers. The cytoplasm isseparated into inner and outer portion by the fibril medulla, its outer is roughlyequivalent to the cortical portion of the other groups and thickness is about1.4μm.There are many mitochondria beneath the pellicle. They distribute within the innerportion of the cytoplasm and close to the fibril medulla. By the TEM is also shown:beneath the pellicle, the outer layer of cytoplasm, there are two types of circularstructures. A class is within the light-colored homogeneous, about0.7μm in diameter.The other is within the deep-colored homogeneous, about0.5μm in diameter. They maybe two kinds of cortical granules. By the SEM is also shown: there are many sizes ofapproximately4×2.5μm,3.5μm ellipsoidal and globular structures in the inner layer ofcytoplasm which is beneath the pellicle. They are likely to be mitochondria.