Мікроскопічні зміни в тонкій кишці котів за інфекційного перитоніту

Abstract

FIP is widespread throughout the world. It has been found that about 25% of cats living alone at home and 75-90% of cats living in groups are seropositive to this coronavirus (Cave, Golder, Simpson, & Addie, 2004; Pesteanu-Somogyi, Radzai, & Pressler, 2008). However, morphological changes at the FIP are not fully described. The purpose of the work was the detail investigation of microscopic changes in the small intestine of cats at the infectious peritonitis. The task of the study was to establish the microscopic changes in the mucosa, submucosa, muscular layer and serosa of the various parts of small intestine at the infectious peritonitis. We conducted a dissection of 26 cats of different breeds and age, which died because of infectious peritonitis. In carrying out a dissection for histological research fragments from different parts of the small intestine (middle part of the duodenal, cranial, middle and caudal third of the jejunum, cranial and caudal halves of the ileum) were selected. Selected fragments were fixed in 10% neutral (pH 7.2) aqueous formalin solution, dehydrated in ethanol of increasing concentration (600, 700, 800, 960, 1000) and was embedded in paraffin. Slides with the thickness of 7 - 10 micrometers were painted by hematoxylin and eosin. In dissection of 19 cats we established a mixed form of infectious peritonitis (73.1%), and in 7 cats – a dry form of this disease (26.9%). At the histological examination of the small intestine of cats which died because of infectious peritonitis we have found that microscopic changes in mixed and dry forms of the disease in different parts of the small intestine were similar. The most expressive microscopic changes are found in the serosa, and the least expressive – in the mucosa. The gradual decrease in the degree of microscopic changes in the direction from the serosa to the mucosa shows that such changes were caused by a factor, which acts from the abdominal cavity. On isolated sites of small intestine, the destruction of mesothelial cells was established, and for many sites of small intestine the pronounced metaplasia of these cells was established. These cells turned into columnar epithelial cells, which formed quite large cellular fields on the outer surface of the small intestine. At the same time, the cells themselves increased significantly in size. The long axis of the columnar mesothelial cells was oriented perpendicularly to the outer surface of the wall of the small intestine. The cytoplasm of modified mesothelial cells was distinctly basophilic. The nuclei had an oval, wrong or rounded shape. In some cases, there was a discomplexation of adjacent modified mesothelial cells. They lost contact with each other and between them there were quite significant intervals. In most cases, the close contact of modified mesothelial cells with the basal membrane was preserved; however, some cells partially lost contact with the basal membrane. Apical cytoplasm (turned to the abdominal cavity) of the part of modified mesothelial cells formed a brush border. In other layers of the wall of the small intestine microscopically mainly disorders of blood circulation, edema and infiltration with lymphocytes and less monocytes are established.