Effect of a mercurial fungicide on the gonadal development of the teleostean fish Channa punctatus (Bloch)

Environmental estrogenic effects and gonadal development in wild goldfish (Carassius auratus)

“…Lazier et al (1996) reported that treatment of mature female tilapia (Oreochromis niloticus) with high levels of androgen (17α-methyltestosterone, 17αMT) resulted in a pronounced decline in plasma VTG levels and the action of 17αMT at the level of hypothalamicpituitary, at which androgen mimics E2 negative feedback or has direct negative feedback effects through the binding androgen receptor. GSI decreases were also found in various adult male fish species exposed to contaminants without estrogenic activity such as metals (mercury, cadmium and copper; Sehgal et al 1984;Ram and Sathyanesan 1986;Singh 1989;Pundir and Saxena 1990) and pseudoestrogen (Gimeno et al 1998). Although the testicular weight is a useful criterion to quantify sperm production since spermatozoa forms the majority of cells in the mature testis (Billard 1986), histological analysis provides a direct evidence to confirm the gonadal development stage of goldfish.…”

Mercury-induced reproductive impairment in fish

“…The morphological effects of mercurials on the pituitary gonadotroph in murrel and walking catfish have been studied by several groups. Histological analyses demonstrated that compared to controls, gonadotrophs were smaller, appeared to be inactive, and were fewer in number in both species of fish exposed to 10 to 50 μg/L of methylmercury, inorganic mercury, or a mercurial fungicide for six months [25,44–46]. The mercury‐induced inhibition of gonadotropic activity was correlated with impaired gonadal development.…”

“…Compared to control fish, testicular growth and spermatogenesis in murrel were arrested following exposure to inorganic mercury (10 μg/L) or a mercurial fungicide (200 μg/L) for six months [25,44,45]. Necrotic areas were visible within the testes of fish exposed to the mercurial fungicide, suggesting direct cytotoxic effects [44]; however, no obvious signs of degeneration were observed after inorganic mercury exposure [45]. Spermatogenesis also was inhibited and GSI decreased in male walking catfish after 180 d of exposure to organic and inorganic mercury at 30 to 50 μg/L [49].…”

“…From these experiments, it can be concluded that both inorganic and organic mercury exposure via a variety of exposure routes can arrest gonadal development in male fish. This effect may be cytotoxic in nature, because effects at the level of the cell include structural alterations in Leydig cells [25,44,45] and necrotic cell death [50,51]. The inhibition of spermatogenesis in the murrel was correlated with small and inactive gonadotrophs of the pituitary [25,45].…”

“…Murrel testes undergoing spermiation contain active interstitial cells characterized by large, rounded nuclei with prominent nucleoli. In contrast, inactive and atrophied interstitial cells were observed in murrels exposed to inorganic mercury (10 μg/L) or a mercurial fungicide (200 μg/L) for six months [25,44,45,62]. Interstitial cells were inactive and showed signs of degeneration, including atrophy and pyknosis in the male walking catfish, after mercury exposure [49].…”