nucleolus


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Related to nucleolus: Smooth endoplasmic reticulum

nucleolus

 [noo-kle´o-lus] (L.)
a rounded refractile body in the nucleus of most cells, which is the site of synthesis of ribosomal RNA, becoming enlarged during periods of synthesis and smaller during quiescent periods; multiple nucleoli occur in some cells.

nu·cle·o·lus

, pl.

nu·cle·o·li

(nū-klē'ō-lŭs, -lī), Avoid the mispronunciation nucleo'lus.
1. A small, rounded mass within the cell nucleus where ribosomal ribonucleoprotein is produced; it is usually single, but there may be several not bound to membrane accessory nucleoli besides the principal one. The nucleolus is composed of a meshwork (nucleolonema) of microfilaments and granules and the pars amorpha, now shown to have microfilaments also.
2. A more-or-less central body in the vesicular nucleus of certain protozoa in which an endosome is lacking but one or more Feulgen-positive (DNA+) nucleoli are present; characteristic of certain sporozoans, flagellates, opalinids, dinoflagellates, and radiolarians among the Protozoa. The chromatin material is distributed throughout the nucleus rather than peripherally, as in the endosome type of nucleus of Entamoeba.
[L. dim of nucleus, a nut, kernel]

nucleolus

(no͞o-klē′ə-ləs, nyo͞o-)
n. pl. nucleo·li (-lī′)
A small body in the nucleus of a cell that contains protein and RNA and is the site for the synthesis of ribosomal RNA and for the formation of ribosomal subunits.

nu·cle′o·lar (-lər) adj.

nu·cle·o·lus

, pl. nucleoli (nū-klē'ŏ-lŭs, nū-klē'ō-lī)
A small, rounded mass within the cell nucleus where ribonucleoprotein is produced.
[L. dim of nucleus, a nut, kernel]

nucleolus

A small, dense rounded body found in the nucleus of most cells. The nucleolus generates RIBOSOMES and is the site of the transcription of ribosomal RNA. The size and number of nucleoli in a cell nucleus vary with the amount of protein synthesized by the cell.

nucleolus

(pl. nucleoli) an organelle found within the nuclei of EUKARYOTES, that contains RIBOSOMAL RNA and is associated with that part of the chromosome which codes for rRNA. Each nucleus contains one or more nucleoli, which appear darkly stained in preparations.
References in periodicals archive ?
Large and round nucleoli were still observed, and follicular cells were flatter, and only one had a prominent and rounded nucleolus. In the late phase of this stage, yolk granules occurred in germinal vesicle migration oocytes, which were characterized by a large size and a high number of oocytes (Figs.
No significant correlation was found between the different causes of death and the nucleolus identification ([chi]: p=0.7)
phyllinus shows a simple epithelium formed by small cuboidal cells with a central spherical nucleus with clumps of condensed chromatin and a prominent nucleolus. The lumen surface of cells is covered by a cuticular layer (Fig.
At this stage, the nucleolus was approximately 8 [micro]m and it still assumed a dark blue color on staining, although it was a lighter shade than that of stage 2 oocyte nuclei.
Early phase: Oocytes displayed a remarkable increase in size, with an intense basophilic ooplasm, a large nucleolus and a high nucleus: cytoplasm ratio (Fig.
The percentage of cells with one nucleolus varied from 82.47% to 84.23% and those with two nucleoli varied from 12.31% to 15.85%.
The electron-dense material presents morphological features of a nucleolus. The nuclear envelope presents numerous pores and it is possible to observe the passage of material from the nucleoli-like structures into the cytoplasm through the pores (Figure 3c).
Transmission Electron Microscopic observation of a normal liver revealed hepatocytes with well organized nucleus and nucleolus when present was prominent.
1 The Multiobjective Linear Programming Problems and the Generalized Nucleolus
Cancer Research Centre, Canada) gathers material from leading experts in the field to discuss the intranuclear environment, the nucleolus, intranuclear structures and interphase chromosomes.