THE LIVER PHOSPHOLIPIDS OF THE DEVELOPING CHICK EMBRYO

Abstract

The concentrations and fatty acid compositions of the individual phospholipids in the livers of chick embryos on the 13th, 15th, 17th, 19th, and 21st days of incubation were compared with the concentrations and fatty acid compositions of the individual yolk phospholipids. The liver phospholipids contained higher proportions of phosphatidyl ethanolamine, phosphatidyl serine, and diphosphatidyl glycerol, and lower proportions of phosphatidyl choline, than did the yolk phospholipids. There was a constant increment (0.96 mg/day) of phosphatidyl choline in the liver during the period of incubation studied. The phosphatidyl choline, phosphatidyl ethanolamine, and phosphatidyl serine of the liver generally contained higher concentrations of stearic, arachidonic, and docosahexaenoic acids, and lower concentrations of palmitic and oleic acids than did these phospholipid fractions in the yolk. The fatty acid compositions of the sphingomyelin in the liver and yolk were similar. The most pronounced changes in the fatty acid composition of the liver phospholipids during embryonic development were observed in the phosphatidyl choline fraction. These changes suggested that the α-palmitoyl-β-arachidonyl phosphatidyl choline in the liver was gradually replaced by α-stearoyl-β-linoleoyl phosphatidyl choline and a-stearoyl-β-docosahexaenoyl phosphatidyl choline.