Hepatocellular endoplasmic reticulum storage disease in an African elephant (Loxodonta africana).

Large intracytoplasmic inclusions were observed in hepatocytes of a 7-year-old African elephant (Loxodonta africana). The inclusions were oval to polyhedral with either a homogeneous glassy or a granular appearance. They were positive for the periodic acid-Schiff (PAS) reaction. Electron microscopical examination revealed that the inclusions consisted of granular material with moderate electron-density and were membrane-bounded. The findings suggested that the inclusions were derived from endoplasmic reticulum. The light and electron microscopical features were similar to those of endoplasmic reticulum storage disease of the liver in man. Such inclusions have not previously been reported in animals.