Abstract
Over a period of 4 years approximately 60% of the new born and juvenile animals in a breeding colony of tamarins (Saguinus fuscicollis) died a sudden death. Histological examination at necropsy revealed interstitial hepatitis in 22 of the 30 young animals of the present study. The hepatocytes contained intranuclear inclusion bodies in 12 of the 22 cases. Upon ultrastructural examination, tubulovesicular structures and amorphous material were found in the nuclei. The endoplasmic reticulum had proliferated and was closely associated with undulating curved membranes. These morphological alterations resemble those reported in chimpanzees experimentally infected with NANB hepatitis viruses.