Thymus - Atrophy









comment:
Atrophy is characterized by reduced thymus size and weight secondary to thymic lymphocyte depletion. A normal thymus typically has similarly sized lobules, a closely apposed capsule, a densely cellular cortex compared with the medulla, a distinct corticomedullary (CM) junction, and a cortex to medulla ratio of ~1:1:1 (two cortices to the medulla) ( Figure 1









recommendation:
When present, atrophy of the thymus should be diagnosed and graded. If atrophy involves only one lobe or is localized, this should be discussed in the pathology narrative. Induced atrophy must be differentiated from normal involution of the thymus. An animal with potential treatment-related thymic atrophy should be compared with age- and sex-matched concurrent controls. Age of the animal and a clear dose-response relationship will help differentiate between thymic atrophy and normal involution.references:
Elmore SA. 2006. Enhanced histopathology of the thymus. Toxicol Pathol 34:656-665. Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1800589/
National Toxicology Program. 2006. NTP TR-521. Toxicology and Carcinogenesis Studies of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) (CAS No. 1746-01-6) in Female Harlan Sprague-Dawley Rats (Gavage Studies). NTP, Research Triangle Park, NC. Abstract: https://ntp.niehs.nih.gov/go/9303
National Toxicology Program. 2007. Toxicology Studies of Sodium Bromate (CAS No. 7789-38-0) in Genetically Modified (FVB Tg.AC Hemizygous) Mice (Dermal and Drinking Water Studies) and Carcinogenicity Studies of Sodium Bromate in Genetically Modified [B6.129-Trp53tm1Brd (N5) Haploinsufficient] Mice (Drinking Water Studies). NTP, Research Triangle Park, NC. Abstract: https://www.ncbi.nlm.nih.gov/pubmed/18784759
National Toxicology Program. 2010. NTP TR-557. Toxicology and Carcinogenesis Studies of β-Myrcene (CAS No. 123-35-3) in F344/N Rats and B6C3F1 MICE (Gavage Studies). NTP, Research Triangle Park, NC. Abstract: https://ntp.niehs.nih.gov/go/33584
National Toxicology Program. 2010. NTP TR-558. Toxicology and Carcinogenesis Studies of 3,3’,4,4’-Tetrachloroazobenzene (TCAB) [CAS No. 14047-09-7] in Sprague-Dawley Rats and B6C3F1 Mice (Gavage Studies). NTP, Research Triangle Park, NC. Abstract: https://ntp.niehs.nih.gov/go/33564
Pearse G. 2006. Histopathology of the thymus. Toxicol Pathol 34:515-547. Full Text: http://tpx.sagepub.com/content/34/5/515.long
Stefanski SA, Elwell MR, Stromberg PC. 1990. Spleen, lymph nodes, and thymus. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, 369-394.
Ward JM, Mann PC, Morishima H, Frith CH. 1999. Thymus, spleen, and lymph nodes. In: Pathology of the Mouse (Maronpot RR, ed). Cache River Press, Vienna, IL, 333-360.
Web page last updated on: February 03, 2015