Respiratory System

Nose, Nerve - Atrophy

Narrative

Comment:

The olfactory nerves in the lamina propria are bundles of axons from the olfactory neurons whose cell bodies lie in the olfactory epithelium. These nerves are unmyelinated and traverse openings in the ethmoid bone and terminate at the olfactory bulbs. The lesion is characterized by decreased size and number, or complete loss in severe cases (Figure 3), of the olfactory nerves. Atrophy of the olfactory nerves (Figure 1, Figure 2, and Figure 3; compare with normal control in Figure 4) is secondary to loss of olfactory nerve cells from the olfactory epithelium or to damage to the olfactory bulb of the brain. It is most commonly the result of loss of olfactory neurons in the olfactory epithelium, so the lesion almost always accompanies changes in the olfactory epithelium, such as atrophy or respiratory metaplasia. Since these lesions are usually part of a larger spectrum of lesions in the nasal cavity, inflammation and changes to the respiratory epithelium are often present as well.

Recommendations:

Olfactory nerve atrophy should be diagnosed as "Nose, Nerve - Atrophy" whenever present. It should be graded based on the size and number of affected olfactory nerves. Other lesions, including olfactory epithelial atrophy or respiratory metaplasia, should be diagnosed separately. Observation of this lesion should prompt close examination of the olfactory lobe of the brain.

Related Links:

Nose - Olfactory Epithelium - Atrophy

References:

Boorman GA, Morgan KT, Uraih LC. 1990. Nose, larynx, and trachea. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, eds). Academic Press, San Diego, 315-337.

Herbert RA, Leninger JR. 1999. Nose, larynx, and trachea. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, ed). Cache River Press, Vienna, IL, 293-332.

Islam Z, Amuzie CJ, Harkema JR, Pestka JJ. 2007. Neurotoxicity and inflammation in the nasal airways of mice exposed to the macrocyclic trichothecene mycotoxin roridin A: Kinetics and potentiation by bacterial lipopolysaccharide coexposure. Toxicol Sci 98:526-541.

Full Text: http://toxsci.oxfordjournals.org/content/98/2/526.full

Uraih LC, Maronpot RR. 1990. Normal histology of the nasal cavity and application of special techniques. Environ Health Perspect 85:187-208.

Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1568325/

All Images

Nose, Nerve - Atrophy in a female F344/N rat from a subchronic study. The olfactory nerves in the lamina propria are small and decreased in number (arrows), and there is loss of cells in the olfactory epithelium.

Nose, Nerve - Atrophy in a female F344/N rat from a subchronic study (higher magnification of Figure 1). The olfactory nerves in the lamina propria are decreased in size and number (arrows), and there is loss of cells in the olfactory epithelium.

Nose, Nerve - Atrophy in a male B6C3F1/N mouse from a chronic study. No olfactory nerves remain in the lamina propria.

Nose, Nerve - Normal in a female B6C3F1/N mouse from a chronic study. Normal size and number of olfactory nerves are shown for comparison with Figure 3.

Authors and Reviewers

Authors

Rodney A. Miller, DVM, PhD, DACVP
NC Pathology Group Manager
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC

Mark F. Cesta, DVM, PhD, DACVP
Staff Scientist, NTP Pathologist
Cellular and Molecular Pathology Branch
Division of the National Toxicology Program
National Institute of Environmental Health Sciences
Research Triangle Park, NC

Reviewers

Robert R. Maronpot, DVM, MS, MPH, DACVP, DABT, FIATP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC

Ronald Herbert, DVM, PhD
NTP Pathologist
Group Leader, Pathology Support Group
Division of the National Toxicology Program
National Institute of Environmental Health Sciences
Research Triangle Park, NC