Size and lipid composition of chylomicrons of different Svedberg units of flotation.

Chylomicrons from thoracic duct lymph of rabbits which were fed corn oil were separated in a preparative ultracentrifuge into subfractions of different S(f) values in order to compare their size, as determined by electron microscopy, with that expected from ultracentrifugation data. The lipid composition of the chylomicrons of different S(f) values was also correlated with their morphology in order to elucidate more about their structure. Although the diameter distribution of chylomicrons from subfractions of lower S(f) ranges corresponded approximately to the expected size distribution, that of the higher S(f) ranges contained many small particles. The TG:PL ratio showed a highly significant correlation with the V:SA ratio of chylomicrons from all subfractions. The findings were consistent with the hypothesis that, irrespective of the S(f) range of chylomicrons, the core is comprised of TG, while PL is spread as a monomolecular layer on the surface of the particles.