Plasmatubules: fact or artefact?
Plasmatubules are tubular evaginations of the plasmalemma associated with sites where high solute flux occurs between apoplast and symplast. Plasmatubules of the scutellar epithelial cells of germinating barley (Hordeum vulgare L.) have been examined following a variety of fixation methods. Of the aqueous fixations, primary aldehyde fixation with osmium post-fixation and osmium as the primary fixative gave comparable images, whilst potassium permanganate resulted in some distortion of the tissue in general including dilation of the tubular evaginations of the plasmalemma. Freeze-fixation and substitution with acetone and acetone-osmium gave images of the plasmalemma comparable to those obtained by the aqueous aldehyde and osmium methods. The similarity of structure with aldehyde or osmium and freezing as the primary fixation is taken to indicate that plasmatubules are real and not artefacts resulting from the fixation procedure.
Key wordsHordeum (scutellum, plasmatubule) Plasmatubule Scutellum (plasmatubule)
Unable to display preview. Download preview PDF.
- Baker, J.R. (1965) The fine structure produced in cells by fixatives. J. R. Microsc. Soc. 84, 115–131Google Scholar
- Browning, A.J., Gunning, B.E.S. (1977) An ultrastructural and cytochemical study of the wall membrane apparatus of transfer cells using freeze-substitution. Protoplasma 93, 7–26Google Scholar
- Crawley, J.C.W. (1965) A cytoplasmic organelle associated with the cell walls of Chara and Nitella. Nature 205, 200–201Google Scholar
- Fineran, B.A. (1970) An evaluation of the form of vacuoles in thin sections and freeze-etching replicas of root-tips. Protoplasma 70, 457–478Google Scholar
- Fineran, B.A. (1971) Effects of various factors of fixating on ultrastructural preservation of vacuoles in root tips. Cellule 68, 269–286Google Scholar
- Franceschi, V.R. (1981) Membrane structure-function relationships in several characean species. Ph.D. thesis, University of Calfornia, Riverside.Google Scholar
- Glauert, A.M. (1975) Fixation, dehydration and embedding of biological specimens. North Holland Publ. Co., AmsterdamGoogle Scholar
- Harris, N. (1981) Plasmalemmasomes in cotyledon leaves of germinating Vigna radiata L.(mung beans). Plant Cell Environ. 4, 169–175Google Scholar
- Harris, N., Chaffey, N.J. (1985) Plasmatubules in transfer cells of pea (Pisum sativum L.). Planta 165, 191–196Google Scholar
- Harris, N., Oparka, K.J., Walker-Smith, D.W. (1982) Plasmatubules: an alternative to transfer cells?Planta 156, 461–465Google Scholar
- Harvey, D.M.R.(1982) Freeze-substitution. J. Microsc. 127, 209–221Google Scholar
- Heath, I.B., Greenwood, A.D. (1970) The structure and formation of lomasomes. J. Gen. Microbiol. 62, 129–137Google Scholar
- Hereward, F.V., Northcote, D.H. (1972) A simple freeze-substitution method for the study of the ultrastructure of plant tissue. Exp. Cell. Res. 70, 73–80Google Scholar
- Howard, R.J., Aist, J.R. (1979) Hyphal tip cell ultrastructure of the fungus Fusarium: improved preservation by freezesubstitution. J. Ultrastruct. Res. 66, 224–234Google Scholar
- Marchant, R., Moore, R.T. (1973) Lomasomes and plasmalemmasomes in fungi. Protoplasma 76, 235–247Google Scholar
- Marchant, R., Robards, A.W. (1968) Membrane systems associated with the plasmalemma of plant cells. Ann. Bot. 32, 457–471Google Scholar
- Mollenhauer, H.H., Morré, D.J. (1976) Transition elements between endoplasmic reticulum and Golgi apparatus in plant cells. Cytobiologie 13, 297–306Google Scholar
- O'Brien, T.P. (1972) The cytology of cell wall formation in some eukaryotic cells. Bot. Rev. 38, 87–118Google Scholar
- Sievers, A., Heyder-Caspers, L. (1983) The effect of centrifugal acceleration on the polarity of statocytes and on the graviperception of cress roots. Planta 157, 64–70Google Scholar