The lipid droplets in this testicular interstitial cell exhibit little or no osmiophilia. It is likely that the differences in osmiophilia of the lipids are reflections of the differences in the degrees of saturation of their constituent fatty acids. The cisternae of the smooth endoplasmic reticulum are in close apposition to the lipid, creating the erroneous impression that the droplets themselves have a limiting membrane. THE CELL 2nd Edition.