×100. They have similar genetic background and are therefore, not discriminated in practical research. It is characterized by its wide head, long ears, and a tail length that is always less than its body length. It is found most frequently in the subintimal myocardium of the left ventricular wall and is more common in male rats (MacKenzie & Alison 1990). Generally it presents with nodules of splenic tissue present within the mesenteric adipose tissue. How to convert human dose to animal dose? Severe apoptosis is often observed when animals are placed under severe stress or treated with immunosuppressive drugs (Stefanski et al 1990). Accessory spleen is an uncommon background finding in the rat abdomen. Ectopic thymus is a common finding adjacent to the thyroid. Squamous cyst filled with keratin near limiting ridge in the rat stomach. ×100. ×100. of Neoplasms in Wistar Han and Sprague-Dawley Rats Klaus Weber1 Abstract A substantial quantity of data on Sprague-Dawley (SD) and Hannover Wistar rats strains have been published concerning their source, diet, and housing conditions, as well as the incidences of nonneoplastic lesions and neoplasms observed in different laboratories. ×200. Mural mineralization of an artery in the rat lung. Can anyone tell me any differences in term of their behaviour, physical appearance, habit, fur, eyes etc. In recent studies, early indications of marginally improved survivability in Sprague Dawley rats may be attributed to a 2.24). FIGURE 2.26 Proliferation of neuroendocrine cells in bronchiole of rat lung. Occasionally, small foci of neuroendocrine cells in the lung (Fig. Arteritis (polyarteritis, periarteritis, panarteritis nodosa) (Fig. 2.27) (also known as alveolar histiocytosis) within alveoli and terminal airways are observed in both young and old rats. Cholesterol clefts in the rat lung. ×100. Mineralization may occasionally be seen in the walls of the blood vessels of the spleen as well as in the capsule of aging rats (Frith et al 2000b). Arterial thrombosis (not caused by arteritis) occurs occasionally in the lung, kidney, liver and adrenal (Ruben 2000). ×100. Heart valve cysts may occasionally be observed in the heart valves of rats (Fig. 2.26) may be visible in aging rats. Dilatation of submucosal glands of the larynx or trachea may also occur as a background lesion in rats (Renne et al 2009) (Fig. Thymic cysts are often lined by squamous cells or ciliated epithelium. photos, graphs and tables). Multifocal aggregates of alveolar macrophages (Fig. 2.17). Thymic atrophy or involution in the rat thymus. 2.25) are often present in the rat lung and represent an agonal event, particularly in rats killed with carbon dioxide or those that die spontaneously (Renne et al 2003). These may be made up of epithelial tubules or nests in the medullary region of the thymus in older rats. Ordinary two-way ANOVA is based on normal data. Occasionally pleural tags (Fig. ×100. 2.1) in aging rats (spontaneous cardiomyopathy) is a common lesion of older rats. FIGURE 2.34 A hair embolus within an artery in the rat lung, surrounded by inflammatory cells. Glandular cysts (Fig. Schwann cell is associated with axon by forming either myelin sheath or Remak bundles. Pigmented macrophages in the sinuses (Fig. Eosinophilic perivascular infiltration in the rat lung. the manuscript is focused on plant agrobacterium transient expression systems and plant parthenogenesis-related proteins and responses. Foci of minimal, generally mononuclear cell inflammation may be noted below the pleura in the rat lung (Fig. ×100. Animal Diet: NIH #31M Rodent Diet. The aggregates are often subpleural or located in the more peripheral regions of the lung (Boorman & Eustis 1990). A rat strain is created through breeding to produce rats that are similar to each other and … The nonneoplastic lesions and proliferations noted in aging rats are problematic as they can be confused with preneoplastic and neoplastic disease (Johnson 2007). ×100. The lesions consist of perivascular lymphocytes, inflammatory cells and alveolar macrophages in the lung alveoli and the presence of epithelial hyperplasia. Taconic received stock from the NIH Animal Genetic Resource in 1970. ×20. ×100. Thymic cysts (Fig. Multifocal aggregates of alveolar macrophages (Fig. The rat spleen normally has a minimal level of extramedullary hematopoiesis; however, it is very difficult to distinguish between normal and excessive levels of extramedullary hematopoiesis. Although the thymus continues to increase in size initially, it begins to regress and at the end of a carcinogenicity study of two year duration the thymus will be severely depleted (Stefanski et al 1990). ×100. FIGURE 2.4 Cartilage at base of aorta in a rat. ×200. 2.10), particularly the mandibular lymph node, are observed frequently in the lymph nodes of both young and old rats. A strain, in reference to rodents, is a group in which all members are, as nearly as possible, genetically identical. 2.22). The vaso vasorum of the mesenteric arteries of the rat can occasionally be confused with a treatment-related finding (Fig. Taconic Sprague Dawley rats are often used in studying metabolism . Endocardial mesenchymal proliferation in the rat heart. Sebaceous gland ectopia in the oral cavity is observed at the base of the molar teeth (male rats) and between the upper incisors (Bertram et al 1996). Concerning this point however, I really cant answer you. FIGURE 2.21 Minimal apoptosis of the rat thymic cortex. In rats, there are, at present, only four reports of intraoral ‘ectopic’ sebaceous glands in the literature (Bernick & Bavetta 1962, Frandsen 1962, Rulli & Martinelli 1971, Yoshitomi et al 1990). The pathology of the aged rat becomes important in the latter stages of carcinogenicity studies (Chandra & Frith 1992). FIGURE 2.6 Medial hypertrophy in heart artery. ×200. ×200. A Fisher LSD post-hoc test showed the differences relative to the Long–Evans and wild strains as: wild rats
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