Comparative Histological and Histochemical Study of The Ileum and Paneth Cells in Dogs and Sheep

Abstract

Referring to the terminal section of the small intestine, the ileum plays a very important role in nutrient absorption and development of the immune system of the body as well as intestinal homeostasis. The study was conducted to evaluate the histological and histochemical features of ileum of different animal species including dogs and sheep. The collected tissue samples from nearby animal markets were examined histologically using five types of staining techniques including hematoxylin and eosin, periodic acid–Schiff, and immunohistochemical techniques. The study results indicated that the ileum of dogs and sheep has four main layers, including mucosa, submucosa, muscularis externa and serosa. However, the study showed significant differences among these species in thickness of these layers as well as in the morphology of villi and the structure of crypts in the ileum. Regarding Paneth cell presence, dogs were found to have a higher number of the cells at the bottom of the intestinal crypts, which was accompanied by better prepared PAS-positive vesicles in comparison to sheep that had a lower number of Paneth cells and weaker PAS activity. The presence of Peyer patches was higher in case of sheep in the ileum, suggesting differences in intestinal immunity reactions. It seems that the structure of the ileum is dependent on the eating habits of the animals and the developed immunity.