Histopathology unveiling the structural damage in gonads of Catla catla due to freshwater contamination

Abstract

Potentially harmful materials, e.g., heavy metals, pesticides, dyes, and hydrocarbons, are often released untreated into freshwater bodies. When such pollutants are released in large quantities, there may be large-scale, sudden mortalities of aquatic organisms. This study summarizes experimental evidence about the disruption of gonadal development due to freshwater contamination. Adult fish specimens of Catla catla were collected from the River Chenab downstream of the Chakbandi Main Drain (CMD) entrance into the Chenab River. CMD collects domestic and industrial sewage wastes from Faisalabad city and disposes them into River Chenab, polluting this water body. Water samples were analyzed from each site of fish harvest for water quality parameters. Collected fish specimens were subjected to histopathological evaluation to detect the impact of pollution on the gonads of this fish species. The male Catla catla gonads showed marked histopathological alterations such as testes degeneration, generalized tissue degeneration produced by fragmentation and detachment of basement membrane, necrosis, and fibrosis in the testis. A loss of tubular arrangement, rupturing of the blood vessels, delimiting seminiferous lobules, vascular hypertrophy of the interstitial compartment, and appearance of a clustered organization were observed. The follicular epithelium in vitellogenic oocytes, rupturing and detachment of follicular basement membrane tissue with cytoplasmic vacuolization, immature oocytes with scattered yolk droplets, hypertrophied follicular epithelium, interstitial proteinaceous fluid deposition, and structural deterioration of follicles with early oocytes were observed in the ovary.