Harderian Gland - Hyperplasia

Image of hyperplasia in the Harderian gland from a male B6C3F1 mouse in a chronic study
Harderian gland - Hyperplasia in a male B6C3F1 mouse from a chronic study. There is a well-demarcated focus of alveoli that doesn�t compress the adjacent tissue.
Figure 1 of 4
Image of hyperplasia in the Harderian gland from a male B6C3F1 mouse in a chronic study
Harderian gland - Hyperplasia in a male B6C3F1 mouse from a chronic study (higher magnification of Figure 1) The alveoli in the hyperplastic focus are lined by increased numbers of large cells with enlarged nuclei and a slightly different tinctorial quality than surrounding normal cells.
Figure 2 of 4
Image of hyperplasia in the Harderian gland from a male F344/N rat in a chronic study
Harderian gland - Hyperplasia in a male F344\N rat from a chronic study. This hyperplastic focus (arrow) consists of a small cluster of alveoli lined by increased numbers of well-differentiated cells crowded into multiple layers.
Figure 3 of 4
Image of hyperplasia in the Harderian gland from a male F344/N rat in a chronic study
Harderian gland - Hyperplasia in a male F344\N rat from a chronic study (higher magnification of Figure 3). The cells in this hyperplastic focus have a slightly different tinctorial quality than surrounding normal cells.
Figure 4 of 4
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comment:

Harderian gland hyperplasia ( Figure 1image opens in a pop-up window , Figure 2image opens in a pop-up window , Figure 3image opens in a pop-up window , and Figure 4image opens in a pop-up window ) is characterized as a well-demarcated but noncompressive focal area in which alveoli are lined by increased numbers of large cells with slightly different tinctorial quality than surrounding normal cells. Nuclei are often similar to those of normal cells, but in some cases, the nuclei may be enlarged ( Figure 1image opens in a pop-up window and Figure 2image opens in a pop-up window ). The increased cell numbers can result in crowding and multiple cell layers ( Figure 3image opens in a pop-up window and Figure 4image opens in a pop-up window ), and even formation of small papillary projections. The absence of compression or marked nuclear pleomorphism can help distinguish Harderian gland hyperplasia from adenoma. Harderian gland hyperplasia may occur as a reactive sequela to degeneration and inflammation but can also be a primary toxic effect and precursor to Harderian gland neoplasia.

recommendation:

Harderian gland hyperplasia should be diagnosed and assigned a severity grade. Whether the hyperplasia is considered a primary effect or a secondary reactive change should be noted in the narrative, especially if there are treatment-related differences in incidence and/or severity.

references:

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National Toxicology Program. 1997. NTP TR-461. Toxicology and Carcinogenesis Studies of Nitromethane (CAS No. 75-52-5) in F344/N Rats and B6C3F1 Mice (Inhalation Studies). NTP, Research Triangle Park, NC.
Full Text: http://ntp.niehs.nih.gov/ntp/htdocs/LT_rpts/tr461.pdf

National Toxicology Program. 2011. NTP TR-567. Toxicology and Carcinogenesis Studies of Ginseng (CAS No. 50647-08-0) in F344/N Rats and B6C3F1 Mice (Gavage Studies). NTP, Research Triangle Park, NC.
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White V, Sinn E, Albert DM. 1990. Harderian gland pathology in transgenic mice carrying the MMTV/v-Ha-ras gene. Invest Ophthalmol Vis Sci 31:577-581.
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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.
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