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nucleolus Syllabification: nu·cle·o·lus
Pronunciation: /ˌn(y)o͞oklēˈōləs/

Definition of nucleolus in English:

noun (plural nucleoli-ˌlī-ˌlē)

A small dense spherical structure in the nucleus of a cell during interphase.
Example sentences
  • Microscopically, large neoplastic lymphoid cells with prominent nucleoli and frequent mitotic figures occlude small vessel lumina.
  • As the cells separated their chromosomes, the nucleolus also appeared to segregate asymmetrically between mother and daughter cells, with the majority in the mother.
  • The tumor cells were arranged in trabecular and solid patterns with nuclear pleomorphism, prominent nucleoli, and scant basophilic cytoplasm.


Pronunciation: /ˌn(y)o͞oklēˈōlər/
Example sentences
  • In addition to nucleolar prominence, multiple nucleoli and nucleolar margination have also been suggested as diagnostic criteria for prostate cancer.
  • Active transcription of ribosomal DNA is required in all organisms for both nucleolar formation and ribosome biogenesis.
  • The LTR probe uniformly labels the chromosome arms except at the telomeres, nucleolar organizing regions, and centromeres, where the signal is lacking.


Mid 19th century: from late Latin, diminutive of Latin nucleus 'inner part, kernel' (see nucleus).

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