Lipid‐depleted white adipose cells: An electron microscope study

This report presents an electron microscope study of white adipose cells depleted of their lipid inclusion by prolonged low food intake. The tissue was fixed in phosphate‐buffered 1% osmium tetroxide, embedded in Vestopal W, and sections were stained with lead hydroxide. Such cells differ in shape and size from signet‐ring cells. They are ovoid, diminished in size, and the cell surface has become indented in all planes of the cell. The intercellular space is expanded with concentrations of collagen fibers in close association with the cell surface. These changes are presumed to be mechanical events associated with loss of lipid from the cell. Subcellular changes include the appearance of an extremely large number of pinocytotic vesicles and cytoplasmic vesicles similar in appearance, membrane‐bound dense bodies, five‐layered membranous structures, vesiculated bodies, and areas of flocculent material. Mitochondria and nuclei appear to be similar to their counterparts in signet‐ring cells. Observations are discussed with relation to ultrastructural changes reported in other studies in which adipose cells were depleted of fat by acute starvation or experimental deprivation of insulin. It is suggested that intracellular structural changes are probably associated with adaptive alterations in the metabolism of the cell.