micronucleus
the smaller, reproductive nucleus of certain protozoans, in contrast to the larger nutritive macronucleus
Source: Noland, George B. 1983. General Biology, 11th Edition. St. Louis, MO. C. V. Mosby ...
micronucleus In the protistan group known as the ciliates, the small nucleus containing a single copy of the genome that is used for sexual reproduction.
micronucleus A small body of DNA that contains the hereditary information of ciliates (Protista); exchanged between protists during conjugation. It undergoes meiosis before functioning in sexual reproduction.
The micronucleus produces a copy by mitosis.
This copy undergoes repeated rounds of endoreplication producing polytene chromosomes.
"Junk" DNA (like newly-acquired transposons) is removed (by RNA interference).
The micronucleus are involved in sexual reproduction in a process known as conjugation that is shown in Figure 12. The macronucleus disintegrates and the micronucleus undergoes meiosis. Two ciliates then exchange a haploid micronucleus.
 See also: Nucleus, Macronucleus, Organ, Cells, DNA
  
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