Experimental hymenolepiasis of rats: preliminary data on histopathological changes of visceral organs

Pathomorphological changes of intestine, liver, spleen and adrenals of rats experimentally infected with Hymenolepis diminuta are described 24 days post infection. Major structural alterations in intestinal wall include lesions of the mucosa, fusions of villi, damage of the epithelial layer and its replacement by flattened cells with pycnotic nuclei. In addition, tunica muscularis and tunica submucosa become thicker and there are numerous lymphocytes among enterocytes. At moderate infections, the changes in the spleen indicate activation of the lymphopoiesis and enhanced protective functions while, in heavily infected rats, the B zone of the spleen showed signs of emaciation. Liver histology of infected rats showed dilatation of sinusoids and the presence of destructive alterations in the parenchyma, necrotic cells and cells with pycnotic nuclei; in heavily infected animals, the necrotic cells were grouped in foci. In adrenal glands, alterations concern mostly zona fascicularis, which is interpreted as mobilization of cytoplasmic lipid inclusions in order to increase the intensity of the steroid hormone synthesis. The degree and character of histopathological changes depended on the intensity of infection.