Background: Fertility in male animals is an important issue in veterinary medicine. Exposure to severe crowding and fattening may affect the fertility of these animals. Objectives: This study compares the effect of oxidative stress caused by overcrowding or obesity on testicular tissue in male albino mice. Methods: A total of 30 male mice were divided into 3 groups. The first was a control group. The second group was subjected to crowding by cramming 20 mice in a small cage. The third group was fattened by eating a high-fat diet. Morphometric cells and histological measurements of the seminiferous tubule diameter, epithelium thickness, and Sertoli and Leydig cell counts were taken. Results: The crowding group testes showed the presence of necrosis and degeneration of spermatocytes, Sertoli, and Leydig cells. The obese group’s spermatocytes, Sertoli, and Leydig cells had shown severe necrosis, degeneration, and giant cell invasion. Histomorphometric measurements of seminiferous tubule diameter, epithelium-thickness, and Sertoli and Leydig cell counts revealed a considerable reduction in the obese group compared to the other groups. Furthermore, in the crowding and fattening groups, measurements of oxidative stress indicators revealed a decrease in glutathione value in the obese group compared to the control, whereas malondialdehyde rose in the overcrowded and obese groups compared to the control. The results of the immunohistochemical expressions for tumor necrosis factor-α (TNF-α) in the testes of mice revealed weak TNF-α positive expression in the control group, moderate expression in the crowding group, and strong expression in the obesity group. Conclusion: The study suggests that both obesity and crowding can impair testicular function, with obesity having the most significant impact. More research into the mechanisms underlying these effects, as well as potential interventions to improve testicular function in obese or overcrowded animals, is required.

BACKGROUND: Intensive aquaculture, which is always associated with high concentrations of nitrogen pollu-tants, can lead to increased economic damage and energy loss, and increased fish mortality. OBJECTIVES: This study aimed to investigate the histomorphometry of the skin and stress indices of the Nile tilapia on exposure to different concentrations of ammonia. METHODS: In this study, Nile tilapia fingerlings were prepared and kept in the tub for adaptation, oxygenation, and feeding. A Range Finding test was performed on the fishes to find the ammonia killing range. Then, an acute toxicity test was performed on tilapia fish for 96 hours. For sub-lethal toxicity studies, 120 Nile tilapia fry were divided into 4 groups, including three groups based on different percentages of LC50 96 h (10, 20, and 30% LC50 96h) and a control group. The groups were exposed to ammonia for 14 days in an environment with constant tem-perature and pH control. Finally, histological examination and stress indices were performed on fish. RESULTS: The results showed that a higher concentration of ammonia resulted in tissue damage, including dis-coloration and skin blackening, and behavioral changes, including swallowing air from the water surface, decreased appetite and decreased mobility which finally resulted in death in these animals (P≤0.05). The highest and lowest glucose levels were reported for the control group and 2.7 mg/L. In addition, stress indices were significantly in-creased in experimental groups (P≤0.05). CONCLUSIONS: The data obtained from this study showed that increasing the amount of ammonia can lead to irreversible tissue damage to the structure of the skin and other tissues. In addition, the increase in oxidative stress in the Nile tilapia was due to the increase in ammonia, which led to lesions in these fish