Electron micrographs comparing briefly AIM-stimulated versus briefly AIM-stimulated plus OA-treated human preadipocytes.

(a) Short AIM stimulation and simultaneous fixation method, often lead to the appearance of small LDs (approximately 1 µm in diameter) which are completely surrounded by multiple cisternae and layers of smooth ER (white double arrows). Smaller LDs of 0.2– 0.5 µm in diameter without such ER layers can also be seen (right side). Embedded in a meshwork of filaments (black arrows) are mitochondria (M) in the neighborhood of these ER layers with no direct contact to LDs. (b) Addition of OA to the cell media for one day leads to the decay of the droplet surrounding ER layers (here shown with sequential fixation method). Arrowheads mark periodically arranged vimentin cage-like structures seen directly in contact with the LD surface. These regular arrays of anchored IFs have been described already by Franke et al. [15]. Several IF bundles within the cytoplasma and with connections to LDs are marked by arrows. Note, with both treatments and fixation methods, mitochondria (M) are not seen in direct contact to the LDs. Bars: 0.50 µm.