BINDING OF LIPID DROPLETS AND MITOCHONDRIA TO INTERMEDIATE FILAMENTS IN RAT LEYDIG-CELLS

We have examined the distribution of lipid droplets and mitochondria i n relation to the cytoskeletons of Leydig cells in primary culture by using light and electron microscopy on living, intact and detergent-ex tracted cells. After mild extraction with Triton X-100 lipid droplets and mitochondria retained their original distribution within the cell. Double immunofluorescent microscopy showed that both structures co-lo calise with intermediate filaments. Transmission electron microscopy o f intact (unextracted) and mildly extracted Leydig cells showed that i ntermediate filaments are closely associated with mitochondria and lip id droplets. By examination of stereo pairs, intermediate filaments we re shown to establish direct contact with mitochondria and lipid dropl ets. The association of droplets and mitochondria with intermediate fi laments suggests possible mechanisms by which the transport of cholest erol takes place from droplets to mitochondria where this substrate en ters the steroidogenic pathway.