Abstract
Analysis of high-speed (150 frames/sec) cinematographs of the filling and expulsion of the water expulsion vesicle of Tetrahymena pyriformis shows that the vesicle fills as water is pumped into it by contractions of at least four ampullary sacs which are continuous with the endoplasmic reticulum. When filled, the vesicle is pressed against its two excretory pores by cyclotic movements of the cytoplasm. This pressure closes the apertures of the ampullae, preventing backflow from the vesicle into them, and also spreads the pellicle of and at the pore, thereby stretching and rupturing the pore-sealing membrane. The vesicle is then invaginated by the cytoplasmic pressure, driving fluid out of the pore. The pore-sealing membrane then reforms, apparently by constriction, and the vesicle is again filled. Electron micrographs show that crisscrossed pore-microtubules extend from the pore to the openings of the ampullae, anchoring the vesicle in place. Each pore is surrounded by a stack of at least 11 ring-microtubules, to which the anchoring pore-microtubules are attached. The pore-microtubules appear to exert tension which assists in spreading the pore, aiding cyclotic pressures in rupturing the pore-sealing membrane. A possible mechanism for the cyclotic pressure and ampullary contraction is proposed.
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Selected References
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- Cameron I. L., Burton A. L. On the cycle of the water expulsion vesicle in the ciliate Tetrahymena pyriformis. Trans Am Microsc Soc. 1969 Jul;88(3):386–393. [PubMed] [Google Scholar]
- Dunham P. B., Stoner L. C. Indentation of the pellicle of Tetrahymena at the contractile vacuole pore before systole. J Cell Biol. 1969 Oct;43(1):184–188. doi: 10.1083/jcb.43.1.184. [DOI] [PMC free article] [PubMed] [Google Scholar]
- ELLIOTT A. M., BAK I. J. THE CONTRACTILE VACUOLE AND RELATED STRUCTURES IN TETRAHYMENA PYRIFORMIS. J Protozool. 1964 May;11:250–261. doi: 10.1111/j.1550-7408.1964.tb01752.x. [DOI] [PubMed] [Google Scholar]
- LUFT J. H. Improvements in epoxy resin embedding methods. J Biophys Biochem Cytol. 1961 Feb;9:409–414. doi: 10.1083/jcb.9.2.409. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Organ A. E., Bovee E. C., Jahn T. L. Adenosine triphosphate acceleration of the nephridial apparatus of Paramecium multimicronucleatum. J Protozool. 1968 Feb;15(1):173–176. doi: 10.1111/j.1550-7408.1968.tb02106.x. [DOI] [PubMed] [Google Scholar]
- Organ A. E., Bovee E. C., Jahn T. L. The mechanism of the nephridial apparatus of Paramecium multimicronucleatum. II. The filling of the vesicle by action of the ampullae. J Cell Biol. 1969 Feb;40(2):389–394. doi: 10.1083/jcb.40.2.389. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Organ A. E., Bovee E. C., Jahn T. L., Wigg D., Fonseca J. R. The mechanism of the nephridial apparatus of Paramecium multimicronucleatum. I. Expulsion of water from the vesicle. J Cell Biol. 1968 Apr;37(1):139–145. doi: 10.1083/jcb.37.1.139. [DOI] [PMC free article] [PubMed] [Google Scholar]
- SIMARD-DUQUESNE N., COUILLARD P. Ameboid movement, I. Reactivation of glycerinated models of Amoeba proteus with adenosinetriphosphate. Exp Cell Res. 1962 Oct;28:85–91. doi: 10.1016/0014-4827(62)90314-2. [DOI] [PubMed] [Google Scholar]
- Schmidt-Nielsen B., Schrauger C. R. Amoeba proteus: Studying the Contractile Vacuole by Micropuncture. Science. 1963 Feb 15;139(3555):606–607. doi: 10.1126/science.139.3555.606. [DOI] [PubMed] [Google Scholar]