Ref ID : 388
Harriett E. Smith; Oral Apparatus Structure in the Carnivorous Macrostomal Form of Tetrahymena vorax. J.Protozool. 29(4):616-627, 1982
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The structure of the oral apparatus in the carnivorous macrostomal form of Tetrahymena vorax has been investigated using serial thin section and preparations of isolated oral apparatuses. The cilia of the oral apparatus are organized into an undulating membrane that borders the right and part of the posterior margin of the buccal cavity and three membranelles that project from plateaus on the anterior surface. Each membranelle consists of one short row and two longer rows of hexagonally packed kinetosomes. The organization of the microtubules of the oral ribs is identical to that in the T. vorax microstomal cell type. However, the first oral rib originates near the first kinetosome at the anterior end of the undulating membrane. The fine filamentous reticulum that underlies part of the oral ribs in the macrostomal cell type is not striated, unlike the reticulum in the microstomal form. A band of filaments similar to the fine filamentous reticulum extends around the anterior margin of the large cytostomal opening that occupies most of the posterior part of the oral cavity. The single row of microtubules along the left side of the oral cavity and cytostome also has filaments associated with it. A major difference between the microstomal and macrostomal forms in the structure of the oral apparatus is in the oral connectives. The macrostomal cell type contains only a single cross-connective that joins the three membranelles and the anterior portion of the undulating membrane. The posterior or peripheral connective between the posterior ends of membranelles one and two and the posterior end of the undulating membrane is absent.