Application of an NaOH maceration method to a scanning electron microscopic observation of Ito cells in the rat liver.

A three-dimensional observation of the Ito cells in the rat liver was made by scanning electron microscopy (SEM) with an NaOH maceration method. The treatment with NaOH facilitated the intercellular separation of the specimen and completely removed reticular fibers around the sinusoid. In this way, the entire shapes of the Ito cells located in the perisinusoidal spaces or between the hepatocytes, were exposed under the SEM. The Ito cells were disposed at regular intervals of 30-55 microns all over the hepatic lobule, and surrounded the whole sinusoid with their subendothelial processes. SEM revealed a pattern of branching for the primary processes into secondary and tertiary processes. Furthermore, previously unknown thorn-like processes of the fourth order were also demonstrated. The Ito cells showed sparse microvilli on their surfaces confronting the hepatocytes, and occasional round elevations, these probably corresponding to lipid droplets. SEM also exhibited the relationship between the Ito cells and other types of cells in the liver. The Kupffer cells often interposed between the sinusoidal wall and the subendothelial processes of the Ito cells.