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Pregnant Wistar rats on day 13 of gestation were treated with T-2 toxin at a single oral dose of 2 mg/kg. Rats were sacrificed at 24 and 48 hours after treatment (HAT), and the dams, placenta and fetuses were subjected to histopathological examination. In the dams treated with T-2 toxin, single cell necrosis was observed in the thymus, spleen, liver, stomach, intestines, salivary glands and pancreas. In the liver, fatty change was also observed. In one dam at 24 HAT, hemorrhage from the vagina was observed macroscopically, and hemorrhage in the placenta and single cell necrosis of cytotrophoblasts were observed microscopically. In the fetuses, increase of single cell necrosis was observed in the central nervous system at 24 HAT. At 48 HAT, single cell necrosis of hematopoietic cells and hepatocytes was also increased in the liver. These results indicate that T-2 toxin may induce changes with similar histopathological nature in dam's organs, placentae and fetuses. These results also suggest that changes observed in the fetuses are caused by the direct effect of T-2 toxin. (J Toxicol Pathol 2003; 16: 59-65)

Connexin32 (Cx32), one of the components of gap junction intercellular communication, is commonly detected by the fluorescent antibody method, although this method has some defects when conducting detailed histopathological investigations. In order to develop a new method to improve the fluorescent antibody method, the optimal immunohistochemical procedure on formalin-fixed paraffin-embedded sections was examined. According to the results, the localization of Cx32 was observed on sections prepared with the Dako catalyzed signal amplification (CSA) method after 0.2% protease digestion for 30 minutes after a 3-day or 6-month fixation. As the CSA method is highly sensitive and based on signal amplification by biotinylated tyramide, the localization of Cx32 was clearly shown on the cell membranes of hepatocytes. In fact, by this CSA method, a decrease in the signals of Cx32 was shown in the liver of rats treated with phenobarbital or in hepatocellular adenoma, which were consistent with previous reports using cryosections. In conclusion, the CSA method is considered an appropriate method for the detection of Cx32 in formalinfixed paraffin-embedded sections. (J Toxicol Pathol 2006; 19: 151-154)