Abstract
By differentiating into mature adipocytes, 3T3-L1 cells can be utilized as a model cell line to investigate (pre)adipocyte function in vitro. Here, we present a protocol for combining qualitative and quantitative analysis of lipid droplets in mature 3T3-L1 adipocytes using oil red O. We describe steps to differentiate 3T3-L1 preadipocytes to adipocytes and give detailed procedures to determine total lipid amount as well as lipid droplet size and number using microscopic devices and an ImageJ macro. For complete details on the use and execution of this protocol, please refer to Kaczmarek et al.1.