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Thyroid Gland, Follicle - Dilation
Thyroid gland, Follicle - Dilation in a male B6C3F1 mouse from a chronic study. There is a single dilated follicle (arrow).
Figure 1 of 4
Thyroid gland, Follicle - Dilation in a male B6C3F1 mouse from a chronic study. This higher magnification of Figure 1 shows the flattened epithelium lining the dilated follicle.
Figure 2 of 4
Thyroid gland, Follicle - Dilation in a male F344/N rat from a chronic study. There is dilation of several adjacent follicles.
Figure 3 of 4
Thyroid gland, Follicle - Dilation in a male F344/N rat from a chronic study. Higher magnification of Figure 3 shows the flattened epithelium of the dilated follicles and pigmented macrophages in one of the follicles (arrow).
Figure 4 of 4
comment:
One or more dilated follicles occur as a common and age-associated change in mouse and rat thyroids. Affected follicles may have pale ( Figure 1
and
Figure 2
) or absent colloid, and exfoliated cells may be present in the lumen. The dilated follicles are frequently seen at the periphery of the thyroid gland (
Figure 3
and
Figure 4
). Dilated follicles are lined by low cuboidal to flattened epithelium.recommendation:
Documentation and grading of dilated follicles are recommended. The diagnosis should indicate whether the dilation is bilateral, with a severity grade based on the more severely affected thyroid gland. The presence of cells within the lumens of the dilated follicles need not be diagnosed separately unless warranted by severity.references:
Hardisty JF, Boorman GA. 1990. Thyroid gland. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, 519–536. Abstract: http://www.ncbi.nlm.nih.gov/nlmcatalog/9002563
Hardisty JF, Boorman GA. 1999. Thyroid and parathyroid glands. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, Boorman GA, Gaul BW, eds). Cache River Press, Vienna, IL, 537–554. Abstract: http://www.cacheriverpress.com/books/pathmouse.htm