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

an area of nuclear DNA containing genes that code for RIBOSOMAL RNA. The area is associated with the NUCLEOLUS.
References in periodicals archive ?
An improved technique for selective silver staining of nucleolar organizer region in human chromosomes.
The nucleolar organizer regions are chromosomal loops of DNA involved in ribosomal synthesis.
Nucleolar organizer regions, G- and C-bands in some Brazilian species of Didelphidae.
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., 2003).
Nucleolar Organizer Regions (NORs) Number, Ratio Dark:Clear Cells, Mean Nuclear Diameter ([micro]m) and Ratio of Nucleus: Cytoplasm (mean [+ or -] SD) in Smears of Ascitic Ehrlich Tumor in Female Mice, Hypothyroid and Euthyroid Ovariectomized and Non-ovariectomized, 10 Days after Tumor Inoculation Hypothyroid Ovariectomized Non-ovariectomized Variable (n = 10) (n = 10) No.
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.
Afterwards, the application of differential staining techniques such as Ag-NORs for nucleolar organizer regions, C-banding for heterochromatin or G-banding for individual chromosome identification allowed the identification of specific chromosome pairs in the karyotypes of bivalve species (see Thiriot-Quievreux 2002, for review).
A maximum of 12 nucleolar organizer regions (NOR) bearing chromosomes were visualized, with the NORs located terminally on the short arms of one pair of medium sized metacentric chromosomes, and on five small-sized acrocentric chromosome pairs.
Most of the cytogenetic studies in oysters so far have focused on karyotyping, chromosome banding, and NOR (nucleolar organizer regions) staining in Ostrea species (Insua and Thiriot-Quievreux, 1991; Li and Havenhand, 1997).