U.S. flag

An official website of the United States government

Dot gov

The .gov means it's official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you're on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Skip to Main Navigation
Skip to Page Content
Skip to Atlas Navigation

Eye, Sclera - Metaplasia, Osseous

Image of sclera metaplasia, osseous in the eye from a male F344/N rat in a chronic study
Eye, Sclera - Metaplasia, Osseous in a male F344/N rat from a chronic study. There are two foci of focal osseous metaplasia (arrow) in the sclera.
Figure 1 of 2
Image of sclera metaplasia, osseous in the eye from a male F344/N rat in a chronic study
Eye, Sclera - Metaplasia, Osseous in a male F344/N rat from a chronic study (higher magnification of Figure 1). This higher magnification image shows a discrete focus of well-differentiated, mineralized bone (osseous metaplasia) in greater detail.
Figure 2 of 2
next arrow
View all images

comment:

Osseous metaplasia of the sclera is an incidental aging change that occurs frequently in Fischer 344/N rats, less often in other common rat strains, and seldom if ever in mice. It consists of single to multiple, discrete foci of well-differentiated, mineralized bone. Occasionally, similar scleral foci of cartilage are observed (cartilaginous metaplasia). These innocuous structures do not incite pathologic changes in the sclera or adjacent tissues.

recommendation:

Scleral osseous metaplasia should be diagnosed only if treatment related, but it does not need a severity grade (i.e., it should be recorded as "present").

references:

National Toxicology Program. 2007. NTP TR-543. Toxicology and Carcinogenesis Studies of α-Methylstyrene (CAS No. 98-83-9) in F344/N Rats and B6C3F1 Mice (Inhalation Studies). NTP, Research Triangle Park, NC.
Abstract: https://ntp.niehs.nih.gov/go/28010

Yoshitomi K, Boorman GA. 1990. Eye and associated glands. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, CA, 239-260.
Abstract: https://www.ncbi.nlm.nih.gov/nlmcatalog/9002563

Back to top

Web page last updated on: October 24, 2014