Euphorbia royleana, a botanical pesticide affects ultimobranchial gland of the catfish Heteropneustes fossilis

Heteropneustes fossilis were subjected to high and low doses of the latex of Euphorbia royleana for short-term and long-term exposures, respectively. The blood was analyzed for plasma calcium levels, and the ultimobranchial glands fixed and examined. Serum calcium levels declined after 48 h following short-term exposure, and this decrease continued until the end of the experiment. The ultimobranchial cells exhibited a decrease in the cytoplasmic staining response after 96 h following treatment, and the nuclear volumes slightly decreased. Chronically exposed fish also exhibited a decline in serum calcium levels, but much later, on day 7, again progressively declining until the close of the experiment. Up to day 14 following treatment there was no change in histological structure of the ultimobranchial glands, but then there was a decrease in nuclear volume and the cytoplasm displayed a weak staining response. There was some vacuolization and degeneration.