Definition of companion cell in English:
companion cell
noun
Botany(In the phloem of flowering plants) a specialized elongated cell, one or more of which is typically connected to, and regulates the movement of substances into and out of, each sieve cell; (in early use also) †a cell that has recently divided from another (obsolete).
Origin
Mid 19th century. In later use after German Geleitzelle.
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