Formation and disintegration of lipid droplets associated with cell organelles, especially smooth-surfaced endoplasmic reticulum in the white adipose cell

Abstract

Although a number of ultrastructural studies on the white adipose cell have been reported, not a few unsolved problems still remain on the morphological and functional relationships between formation or disintegration of lipid droplets and cell organelles in those cells. In order to re-examine such the points, we have made electron microscopical studies on the epididymal adipose cells from normal and starved Wistar adult rats, and on these cells from rats refed ordinary animal food or given only lipid without carbohydrate after a period of starvation. Additionally, for the same purpose we have observed the ultrastructure of developing and differentiating fat cells in the epididymal adipose tissue of rats ranging from newborn to 5 weeks old.The adipose cell from normal adult rats shows that the peripheral cytoplasm which envelopes a central large lipid mass contains well-developed cell organelles and occasionally small lipid droplets. These lipid droplets have no limiting membrane, but are often observed to be closely encircled by fenestrated profiles of smooth-surfaced endoplasmic reticulum (SER) which connects with a part of rough-surfaced endoplasmic reticulum (RER) in places (Fig. 1).