A scanning electron microscopic study on hepatic changes induced by mouse hepatitis virus-2.

No significant changes in the structure of the liver were seen until 9 hr after the inoculation of mouse hepatitis virus-2 (MHV-2) into mice. At the 24 hr stage, distinct swelling of hepatocytes and narrowing of sinusoidal lumina were observed from the middle to the central area of the hepatic lobules. Most of the Kupffer cells were swollen. Their villous projections were decreased in number, and the remaining projections became like blebs. Virus particles appeared from this stage in the hepatocytes, the Kupffer cells and the space of Disse. At the 48 hr stage, parenchymal necrotic foci were present in the central and the middle area of the lobules. The necrotic change was increased from 72 hr after inoculation, and was followed by submassive or massive necrosis. It is suggested that hepatic necrosis in both the central and the middle area, or in either area, of the lobules was advanced by aggravation of the sinusoidal microcirculation, as a result of the swelling of the hepatocytes and the Kupffer cells in addition to the direct affection by virus. Fine granulation was observed on the surface of most of the central flagella of the bile duct. Some flagella were degenerated, and came in part to be a fibrillar net.