1. A nucleus that occupies a relatively large portion of the cell, or the larger nucleus where two or more are present in a cell. SYN: meganucleus. 2. The larger of the two nuclei in ciliates, which governs vegetative metabolic functions and not reproduction. SYN: somatic nucleus, trophic nucleus, trophonucleus. SEE ALSO: micronucleus (2).
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mac·ro·nu·cle·us .mak-rō-'n(y)ü-klē-əs n, pl -clei -.ī also -cle·us·es a relatively large densely staining nucleus of most ciliate protozoans that is derived from micronuclei and controls various nonreproductive functions compare MICRONUCLEUS
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mac·ro·nu·cle·us (mak″ro-nooґkle-əs) [macro- + nucleus] in ciliate protozoa, the transcriptively active, polyploid nucleus, much larger than the micronucleus, that governs the organism's vegetative processes and is responsible for its phenotype. Called also trophic nucleus and trophonucleus.Medical dictionary. 2011.