Hepatic sinwoidal lining cells were isolated from mature d e rats (12 months old) and cultured in order to clarify the characteristics of the Ito cells (fat-storing ce~lls). Deomin staining was used as a marker in the isolation of the Ito cells, and a highly purified desminponiave cell traction was obtained. Less than 10% of the dasepia-goeitive cells were positive for vitamin A autofluoremcence. However, the number of vitamin A-positive cells increased with vitamin A treatment, and they extended to over half of the desmin-positive cells by the tiret week of vitamin A treatment. The cultured Ito cells were poeitive for both desmin and vimentin stainings. On the other hand, Kupffer and endothelial cells were paeitive only with vimentin staining. Ito cells lost their fat droplets after repeated subculturing. The electron dcmmpic featurea of the Ito cells became similar to t h e e of myoiibroble&s, except for the absence of dense bodeo, Wcating that the Ito cells may have possibly tranaierned into myofibroblasts. Collagen fibers were o a a e b d y found in the extracellular space. These re-Saws indQnetn that Ito cells retain both their myogenic and !&rogemic properties, and that lipocytee or myofi-brobLde may be desmin-positive cells which maintain spediac fhnctions. Furthermore, staining of the intermebi.te Ellaaaents is useful in the identification of Ito cells, and a highly purified Ito cell fraction can be saeily obtained using desmin staining as a marker.