A term formerly applied to a group of phosphatidic esters resembling lecithin but containing either 2-ethanolamine or l-serine in the place of choline; these are now known as phosphatidylethanolamine and phosphatidylserine. These esters are widely distributed in the body, especially in the brain and spinal cord, and are used as local hemostatics and as reagents in liver function test. SYN: kephalin.