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Acro-P-Arm Probe

Catalogue Numbers
LPE NOR (10 tests)
LPE NOR-S (5 tests)

The Nucleolar Organiser Regions (NOR) contain clusters of genes which code for the three largest structural rRNA molecules (5.8S, 18S and 28S).

These rRNA genes are critically important for the viability of the cell and represent around 0.5% of the human diploid genome. They are found in the short arm of the acrocentric chromosomes and are the region around which the nucleoli develop at the end of mitosis1.

A NOR can translocate to a terminal region of another chromosome. In rare instances this can be pathogenic, particularly when the translocation has led to a deletion at the tip of the recipient chromosome2. It has been suggested that the restructuring of the rRNA genes is the most common chromosomal alteration in adult solid tumours3.

In routine cytogenetic analysis, NOR can be used to delineate marker chromosomes through a process of silver staining the NOR (known as AgNOR staining4). However, the technique relies on translation of protein and if this is not present, conventional silver staining will not stain the NOR. Cytocell's FISH probe has been developed to overcome this problem so that presence of the acrocentric chromosomes in the marker can be detected.


1. McClintock B, Z Zellforsch Mikrosk Anat 1934;21:294-328

2. Gardner RJM, Grant R Sutherland, Chromosome abnormalities and genetic counseling, Oxford University Press p240 2004

3. Stults DM et al., Cancer Res 2009;69(23):9096-104

4. Goodpasture C, Bloom SE, Chromosoma 1975;53:37-50

Microscope Images

Acro P Arm Probe Magnified


This product is intended to be used on Carnoy’s solution (3:1 methanol/acetic acid) fixed peripheral blood samples.