Figure 1.

Bile duct hyperplasia after repeated oral dosing of rats with a Petasites hybridus extract (Petadolex) for six months. (A). HE staining of liver sections from control animals that were treated with the vehicle Migylol 812 for six months (A1, A2). Shown in A3 is a control recovery animal which also received vehicle treatment for six months, but was subsequently given a normal laboratory diet for four weeks. No lesions were observed. (B) Animals treated with the Petasites hybridus extract at 45-fold of maximum clinical doses. HE staining of liver sections revealed mild to moderate bile duct proliferations. (C) Animals treated with the Petasites hybridus extract at 90-fold of maximum clinical doses. HE staining of liver sections revealed moderate to marked bile duct proliferations. (D) Recovery animals were treated for six months with the Petasites hybridus extract at 90-fold of maximum clinical doses. Subsequently the recovery animals were given a normal laboratory diet for four weeks. Reversibility of bile duct proliferations was observed but did not resolve within the four weeks of the recovery period. All images are a magnification of 125× and were taken with a Nikon Ni-E microscope, Japan. Image capture was done with the Nikon NIS basic research microscopic imaging software version 4.3. The images were converted into tiff files and compiled in Adobe Photoshop version CS5.