Ultrastructure of cultured hepatocytes from fat- and cholesterol-fed rats

Hepatocytes were enzymatically dissociated from the livers of rats maintained for eight weeks on diets of (1) standard rat chow, (2) chow plus 20% olive oil, and (3) chow plus 20% olive oil and 2% cholesterol. Cells were cultured for up to one week and characterized by phase contrast light microscopy and transmission electron microscopy. Cultured hepatocytes derived from the cholesterol-fed rats (3) were distinguishable by phase contrast light microscopy from those derived from chow-or chow plus olive oil-fed (1 and 2) cells, since they contained numerous refractile cytoplasmic structures. Transmission electron microscopy demonstrated that these structures were lipid droplets. Hepatocytes were observed to accumulate non-membrane bound cytoplasmic lipid droplets in the order control-fed less than olive oil-fed less than cholesterol-fed. In addition to varying quantitatively among the feeding groups, lipid droplets also varied in size and osmiophilia as a function of the feeding regimen. Other than the differential accumulation of lipid droplets, the ultrastructure of the cultured hepatocytes was similar among cells derived from the various feeding groups.