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Observations on the Fine Structure of the Ciliate Dileptus anser
Author(s) -
DUMONT JAMES N.
Publication year - 1961
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1961.tb01234.x
Subject(s) - anatomy , cilium , proboscis , biology , fibril , biophysics , microbiology and biotechnology
Dileptus anser is a relatively large multinucleate ciliate (gymnostome) which bears an anteriorly directed non‐retractable proboscis. On the ventral surface of the proboscis is found a “feeding groove” which is bounded laterally by large feeding cilia. In the ventral mid‐line of this groove is a small fiber which passes from the anterior tip to the cytostome‐cytopharyngeal complex, which is located at the base of the proboscis. Electron micrographs show that this fiber is composed of smaller fibrils. These smaller fibrils are attached to the kinetosomes of the feeding cilia on both the right and left sides of the larger fibril bundle. Thus, the mid‐ventral fibril bundle lies between two ciliary rows and provides fibrils for kinetosomes on both its right and left sides. Therefore, it seems likely in the case of this gymnostome, that there exists an exception to the rule of desmodexy as postulated by Chatton and Lwoff (1935). The function of these fibrils remains obscure but it is suggested that, in view of their close association with the feeding cilia and the non‐retractable nature of the proboscis, their function may be primarily coordinative. However, the possibility that they may also be concerned secondarily with minor contractions is not excluded. The armature of the cytostome‐cytopharyngeal complex is composed of two distinct systems: (1) a system of fibrils which are apparently kinetodesmal and (2) a system of trichites. The fibrils are thought to be associated with the feeding cilia of the proboscis as well as with those which surround the cytostome. The fibrils extend into the cytoplasm of the armature and are intermingled among the trichites. The tri‐chites are arranged in two concentric cones around the cytostome. In the outermost cone they are larger and arranged in almost single file as opposed to the smaller size and the more or less random orientation of those of the inner cone. They are composed of smaller hexagonally packed rods which measure 170‐180 Å in diameter and are separated by a space of about 100 Å.