Acceptors of fatty acid for glyceride synthesis in guinea pig mammary gland.

T w o PATHWAYS have now been described for the biosynthesis of glycerides in mammalian tissues. In the pathway which exists in liver (1, 2) and adipose tissue (3), triglycerides are synthesized from L-a-glycerophosphate via L-a-phosphatidic acids and D-a,@-diglycerides. More recently it has been found that a second pathway involving the direct acylation of monoglyceride exists in intestinal mucosa (4-7), kidney (8), liver (8 ) , and aorta (9). During the course of our studies on fat metabolism in the lactating mammary gland (10-12), it became necessary to investigate the pathways of biosynthesis of glycerides in this tissue. Evidence will be presented in this paper for the existence in lactating mammary tissue of both known pathways of glyceride synthesis. Part of this work was presented at the April 1963 meeting of the Federation of American Societies for Experimental Biology (1 3).