Ref ID : 4206
Tom Fenchel and Bland J. Finlay; The Structure and Function of Muller Vesicles in Loxodid Ciliates. J.Protozool. 33(1):69-76, 1986
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The Muller vesicle is a characteristic organelle of loxodid ciliates. Its structure and development have been investigated using light microscopy and TEM. The organelle consists of a membrane-covered mineral body (the statolith), a vacuole, and various structures derived from the overlying kinety. There is strong evidence that the vesicle functions as a gravity sensor: a) its structure and relative dimensions fulfil the minimum requirements of a functional statocyst; b) its structure bears a close resemblance to the statocysts of some higher animals; c) re-orientation of the cell with respect to gravity produces a gravity-induced displacement of the mineral body, and d) geotaxis in Loxodes can be demonstrated experimentally. The transduction of the signal probably takes place at the level of the two kinetosomes of the organelle, one of which is in close contact with the cell membrane, while the other is connected to the statolith by a fairly rigid stalk containing a bundle of microtubules.