micronucleus
|mi-cro-nu-cle-us|
🇺🇸
/ˌmaɪkroʊˈnuːkliəs/
🇬🇧
/ˌmaɪkrəʊˈnjuːkliəs/
tiny additional nucleus
Etymology
'micronucleus' originates from Greek and Latin: the prefix 'micro-' comes from Greek 'mikros' meaning 'small', and 'nucleus' comes from Latin 'nucleus' (diminutive of 'nux') meaning 'kernel' or 'little nut'.
'micronucleus' was coined in modern scientific/biological usage by combining the Greek-derived prefix 'micro-' with the Latin-derived 'nucleus' and entered scientific English usage to denote a 'small nucleus' in cells; it has been used in biology since the late 19th to 20th century.
Initially it simply meant 'a small nucleus'; over time the term became specialized in biology to refer to specific technical senses (the germline nucleus in ciliates and the small extra nucleus formed by chromosome fragments in cytogenetics).
Meanings by Part of Speech
Noun 1
in certain protozoans (especially ciliates), the smaller of two types of nuclei; the micronucleus contains the germline genetic material and is involved in sexual reproduction and transmission of hereditary information, distinct from the macronucleus which controls everyday cell function.
In Paramecium, the micronucleus is responsible for passing genetic information during conjugation.
Synonyms
Noun 2
a small, extra nucleus formed in a cell when chromosome fragments or whole chromosomes fail to be incorporated into the daughter nuclei during cell division; used in cytogenetics as an indicator of genotoxic damage (the micronucleus test).
Exposure to the chemical increased the frequency of micronuclei in the cultured human lymphocytes.
Synonyms
Last updated: 2026/01/14 19:48