Lipovitellenin is obtained as a floating, low density lipoprotein (LDL) by ultracentrifugation of diluted yolk. Several components with varying densities can be separated by fractional centrifugation. The lipid moiety represents 84-90% of the dry matter and consists of 74% triglycerides and 26% phospholipids. The latter contain predominantly phosphatidyl choline (approx. 75%), phosphatidyl ethanol amine (approx. 18 %) as well as sphingo myelin and lysophospholipids (approx. 8%). The molecular weight of lipovitellenin is several million dal. The individual com ponents of this plasma protein are not well characterized.