Fat associated with adipose lipase. The newly synthesized fraction that is the preferred substrate for lipolysis.

The incorporation of fatty acids by adipocyte fat cake was observed. The newly formed lipid was not extracted by petroleum either but remained in the lipase-containing residue. It was the first lipid to be hydrolyzed when the lipase was activated by exposure to the aqueous phase. The data presented indicate that the lipid fraction of the fat layer residue is the active compartment of cell acylglycerol and demonstrate that the compartmentation of acylglycerols into metabolic pools involves a physical separation between them.