Relationship between embryonic and tumor lipids. I. Changes in the neutral lipids of the developing chick brain, heart and liver.

Abstract

AbstractOrgan dry weight, per cent total lipid, per cent neutral lipid, per cent phospholipid, and neutral lipid class composition of embryonic and mature brain, heart and liver were determined at 10, 13, 16, 19, 22, 27 and 53 days after incubation was initiated. All three tissues showed an increase in total lipids from the 10th day to hatching (21st day). The 10th day brain showed relatively high levels of sterol esters which decreased with increased development while free sterol levels increased. Heart free sterol and sterol ester percentages decreased with increassed time, while triglyceride levels increased dramatically after the 16th day. Liver showed a massive accumulation of neutral lipid after the 17th day. The neutral lipid was not triglyceride, as might have been expected, but sterol ester. Liver sterol, sterol ester and triglyceride levels were approximately equal at the 10th and 13th days, after which time sterol ester rose rapidly to more than 90% of the total neutral lipids by the 19th day. The neutral lipid class distributions were characteristically different for each tissue throughout embryonic development. The relative high sterol ester levels in each of the tissues early in development suggests that the high level of sterol esters in neoplastic tissue may be related to the growth process of increasing cell numbers. On the other hand, the absence or the presence of only trace amounts of glyceryl ether diesters in any of the embryonic tissues suggests that the elevated levels of this lipid class in most tumors may be related to the neoplastic process or to conditions resulting from neoplasia.