In ultracentrifugation of lipoproteins, which observation indicates chylomicrons?

• A. Lipid stains
• B. Turbid layer
• C. Creamy layer
• D. Standing plasma test

Answer: (C)

In ultracentrifugation, particles separate by density, and chylomicrons are the least dense lipoproteins because they are rich in triglycerides and large in size. That low density makes them buoyant enough to rise to the very top of the tube, where they form a distinct, creamy (milky) layer. Seeing this top creamy layer is the telltale sign that chylomicrons are present.

Other observations don’t specifically indicate chylomicrons. Lipid stains show lipids in general but don’t distinguish chylomicrons from other lipoproteins. A turbid layer can occur with various lipoprotein mixtures but isn’t diagnostic for chylomicrons, and standing plasma tests aren’t about identifying the top layer formed during ultracentrifugation.