Lesions in the Larynx of Wistar RccHan: WIST Rats |
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| Authors: | Weber Klaus Germann Paul-Georg Iwata Hijiri Hardisty Jerry Kaufmann Wolfgang Rosenbruch Martin |
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| Institution: | 1.Harlan Laboratories Ltd., Zelgliweg 1, 4452 Itingen, Switzerland;2.Nycomed GmbH, Byk Gulden Str. 2, 75467 Konstanz, Germany;3.EPL Experimental Pathology Laboratories Inc., Research Triangle Park, North Carolina 27709, USA;4.Experimental Toxicology and Ecology, BASF SE, GV/TD–Z 470, D-67056 Ludwigshafen, Germany;5.Bayer Schering Pharma AG, GDD-GED-GTOX-Pathology & Clinical Pathology, P.O. Box 101709, D-42096 Wuppertal, Germany |
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| Abstract: | Specific regions in the rat larynx exhibit cellular changes in response to inhaled xenobiotics. These regions include the base of the epiglottis, ventral pouch, and medial surfaces of the vocal processes of the arytenoid cartilages. 1 , 2 In order to collect information on the usefulness of trimming techniques, the influence of different vehicles, the impact of different application routes in toxicity studies, and differences between induced vs. spontaneous lesions, the data obtained from a large number of inhalation and non-inhalation studies performed in Wistar RCCHan(TM): Wist rats at Harlan Laboratories Ltd Switzerland, all evaluated or reviewed by the same pathologist, were compiled for a detailed review. The value of different trimming techniques was deemed to be greatest for transverse and sagittolongitudinal section techniques, as compared to horizontolongitudinally section techniques. The comparison of lesions encountered in control rats of inhalation studies treated with different vehicles did not reveal differences in the type, distribution pattern, incidence and/or severity of spontaneous lesions. The types of lesions were also independent of different application routes in non-inhalation studies compared to inhalation studies. The pattern of spontaneous lesions in the rodent larynx was determined by degenerative and inflammatory lesions starting most often in the submucosal glands by desiccated secretion followed by mineralization and local inflammation or were induced by impacted foreign bodies. Squamous metaplasia was recorded in the respiratory epithelium overlaying the ventral gland as a spontaneous lesion in male Wistar rats from inhalation studies with a maxim of 20.0% in an inhalation oncogenicity study. Induced metaplastic changes recorded in the larynx were reversible. Other induced lesions in inhalation studies consisted of submucosal edema, necrosis, inflammation and/or granuloma. Induced lesions in non-inhalation studies were found to be exclusively related to reflux laryngitis or food impaction. It is concluded, that in rodents induced lesions of the larynx differ in type, distribution pattern, severity and incidence from spontaneous lesions. |
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| Keywords: | spontaneous laryngeal lesions induced laryngeal lesions Wistar RccHanTM: WIST |
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