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companion cell

companion cell A type of cell found within the phloem of flowering plants. Each companion cell is usually closely associated with a sieve element. Its function is uncertain, though it appears to regulate the activity of the adjacent sieve element and to take part in loading and unloading sugar into the sieve element. In gymnosperms a similar function is attributed to albuminous cells, which are found closely associated with gymnosperm sieve elements.

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"companion cell." A Dictionary of Biology. . Encyclopedia.com. 15 Dec. 2017 <http://www.encyclopedia.com>.

"companion cell." A Dictionary of Biology. . Encyclopedia.com. (December 15, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/companion-cell

"companion cell." A Dictionary of Biology. . Retrieved December 15, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/companion-cell

companion cells

companion cells Modified parenchyma, linked to sieve cells by plasmodesmata. Unlike sieve cells, companion cells are nucleated and have many mitochondria. Companion cells may regulate translocation.

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"companion cells." A Dictionary of Plant Sciences. . Encyclopedia.com. 15 Dec. 2017 <http://www.encyclopedia.com>.

"companion cells." A Dictionary of Plant Sciences. . Encyclopedia.com. (December 15, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/companion-cells

"companion cells." A Dictionary of Plant Sciences. . Retrieved December 15, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/companion-cells