Urinary Bladder, Urothelium - Cytoplasmic Granules

Image of cytoplasmic granules in the urinary bladder from a male B6C3F1 mouse in a subchronic study
Fine, eosinophilic cytoplasmic granules in the superficial cells of the urothelium from a male B6C3F1 mouse in a subchronic study.
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Image of cytoplasmic granules in the urinary bladder from a male B6C3F1 mouse in a subchronic study
Eosinophilic cytoplasmic granules from a male B6C3F1 mouse in a subchronic study (higher magnification of Figure 1).
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Image of cytoplasmic granules in the urinary bladder from a male B6C3F1 mouse in an acute study
Cytoplasmic granules-basophilic granules present in the urothelium from a male B6C3F1 mouse in a 28-day study.
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comment:

Cytoplasmic granules may be observed within the most superficial epithelial “umbrella” cells of the urothelium. They rarely occur in the intermediate or basal cells and typically are deeply eosinophilic. The granules may represent a number of reported constituents, such as degradation products, chemicals/metabolites, or mitochondria. The presence of cytoplasmic granules usually elicits no cell response and has not been associated with either preneoplasia or neoplasia.

recommendation:

Cytoplasmic granules should be diagnosed and given a severity grade. If treatment related, any unique characteristics of the granules should be described in the narrative report.

references:

Cohen SM. 2002. Comparative pathology of proliferative lesions of the urinary bladder. Toxicol Pathol 30:663-671.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/12512866

Frazier KS, Seely JC, Hard GC, Betton G, Burnett R, Nakatsuji S, Nishikawa A, Durchfeld-Meyer B, Bube A. 2012. Proliferative and non-proliferative lesions in the rat and mouse urinary system. Toxicol Pathol 40:14S-86S.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/22637735

Suzuki S, Arnold LL, Muirhead D, Lu X, Le C, Bjork JA, Wallace KB, Ohnishi T, Kakiuchi-Kiyota S, Pennington KL, Cohen SM. 2008. Inorganic arsenic-induced intramitochondrial granules in mouse urothelium. Toxicol Pathol 36:999-1005.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/19126794