Histological Structure of the Cyst Wall of Contracaecum larva and the Histopathology in the Stomach of Silurus glanis

Larvae of Contracaecum sp. were found encysted in the stomach of Silurus glanis in three successive stages namely L2, L3 and L4. The cystes were white in color, elongated and their dimensions were 0.50.9 mm. In general, the wall consists of two layers, outer thick and inner thin layers. The outer one consists in turn of collagenous fibers intermingled with epithelial cells, fibroblasts, macrophages and lymphocytes. While the inner layer consist of collagenous fibers, few fibroblasts, lymphocytes and fibrocytes. The most important histological changes due to the infection with this larva is infiltration of inflammatory cells around the cyst and its cavity , which is represented by macrophages, nucleated cells and acidophils, and in same time occurrence of necrosis, and local aggregation of lymphocytes between the muscle bundles. Also, few pycnotic cells were observed and erythrocytes, macrophages and remnants of cells around the larval cuticle, and the presence of blood vessels surrounding the cyst. Furthermore, dwarfness of intestinal glands and destruction of the epithelial tissue were observed.
As regard the carbohydrate, the cyst walls reacted strongly positive with Periodic acid Schiff, Alcian blue and Best Carmine, while the cyst layer reacted negatively with Toludine blue.
Both cyst walls reacted positively with protein detecting technique including Mercury Bromophenol blue and Ninhydrin Schiff, with lipid detecting technique such as Aceton Sudan BlackB, Feulgen reaction, for detecting DNA, finally, strongly reacted by using Von Kossa technique.