nucleolar organizer


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nu·cle·o·lar or·ga·niz·er

the region of the satellites on the acrocentric chromosomes that is active in nucleolus formation.

nucleolar organizer

[no̅o̅klē′ələr]
Etymology: L, nucleolus, little nut kernel; Gk, organon, instrument, izein, to cause
a part of the nucleus of the cell, thought to consist of heterochromatin, that is responsible for the formation of the nucleolus. Also called nucleolar zone, nucleolus organizer.

nucleolar organizer

an area of nuclear DNA containing genes that code for RIBOSOMAL RNA. The area is associated with the NUCLEOLUS.
References in periodicals archive ?
The nucleolar organizer regions are chromosomal loops of DNA involved in ribosomal synthesis.
Functional sexual dimorphism of the nucleolar organizer regions in the tuberomamillary nucleus.
Silver-staining analysis revealed the activity of nucleolar organizer regions (NORs) on the short arms of both acrocentric chromosomes of autosomal pair number 6; the presumptive sex chromosomes did not show NOR activity (Fig.
Nucleolar organizer region (NOR) distribution as a diagnostic marker in oral keratosis, dysplasia and squamous cell carcinoma.
Nucleolar organizer regions (NORs) and myoepitheliomas: A comparison with DNA content and clinical course.
From the nuclear morphometry, and the morphometric analysis of the nucleolar organizer areas, it is possible to optimize the prognosis for a better conduct orientation (Dantas et al.
Smears were also impregnated with silver in order to individualize nucleolar organizer regions (NORs), in accordance with a technique previously described (18) with some modifications proposed by Aubele et al.
The diploid number, chromosome morphology, SDCS type, and behavior of chromosomes during meiosis were determined with conventional staining, and the distribution pattern of the active nucleolar organizer regions (NORs) in the chromosomes was established using silver staining.
edule (Insua & Thiriot-Quievreux 1992) and standard karyotype, and the location of the nucleolar organizer regions were described from Baltic and Mediterranean populations' of C.
This paper describes the diploid number, chromosome formula, and locations of nucleolar organizer regions (NOR) in P.
Abbreviations: CI, centromeric index; FISH, fluorescence in situ hybridization; NOR, nucleolar organizer region.
46 [micro]m (Table 1) without a nucleolar organizer region (NOR) is submetacentric; it has a terminal band and an interstitial band on the short arm; in addition to the centromeric band, a large interstitial band is located near the centromere on the long arm.