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Ultrastructural Studies in the Brown Alga Ectocarpus in Culture: Ageing

Luis Oliveira and Thana Bisalputra
The New Phytologist
Vol. 78, No. 1 (Jan., 1977), pp. 131-138
Published by: Wiley on behalf of the New Phytologist Trust
Stable URL: http://www.jstor.org/stable/2431178
Page Count: 13
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Ultrastructural Studies in the Brown Alga Ectocarpus in Culture: Ageing
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Abstract

Ultrastructural changes associated with ageing of the vegetative sporophytic cells of Ectocarpus are described. Nuclei, endoplasmic reticulum and dictyosomes become reduced or disappear; mitochondria are also much affected. Of all cell organelles, plastids display the most striking alterations. These include the formation and release into the cytoplasm of electrondense material, probably of lipid nature, and the budding off of portions of the plastids. The cytoplasm, congested with a variety of inclusions, shows toward the end of the ageing process the first signs of autolysis (rupture of the tonoplast). Conspicuous wall ingrowths are also formed along the cross and end walls of the cells. Ingrowths that occur at the cross walls do not seem to disrupt plasmodesmatal continuity. The maintenance of symplast continuity is believed to be significant to the progress of the ageing process. The present findings are discussed in relation to available data obtained from other plant studies.

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