RESUMEN
Hydatid cyst (Hydatidosis) is considered one of the parasitic diseases that pose a threat to both animals and humans alike. Objectives: the present study was aimed to investigate cystic echinococcosis in sheep. By employing a variety of specific stains, we sought to uncover the mesmerizing histochemical changes associated with this condition. Twenty lung samples infected with hydatid disease were obtained. The samples were fixed in 10% formalin and processed and then stained with haematoxylin and eosin and some special stains such as Periodic Acid Schiff (PAS), Gomri's aldehyde fuschin, Best Carmine, Van Gieson, Toluidine blue and Alcian blue to investigate the histochemical changes that occurred in the lung tissue. Chemical changes were observed in the lung tissue affected by hydatid cysts, revealing insights into the underlying pathological processes. The presence of hydatid cysts was characterized by encapsulation within the lung tissue, consisting of a laminated layer surrounded by a fibrous membrane. Severe pneumonia was evident, accompanied by the infiltration of inflammatory cells and the presence of necrotic cells containing lytic nucleic acids. These changes resulted in atelectasis (partial or complete lung collapse) and emphysema (destruction of alveolar walls). Despite these pathological changes, intact elastic fibers were observed surrounding the bronchiole, indicating preserved structural integrity. Necrosis of epithelial cells in the bronchiole was also observed, disrupting normal respiratory system functioning. The hydatid cyst has a clear effect on the lung tissue, represented by the histochemical changes that certainly cause damage to the lung and this is reflected in its vital function inside the body.
