Incorporation of Plasma Cholesterol-4-C 14 into Egg Yolk Cholesterol. ∗

Abstract

Summary

These data indicate that the laying hen transfers cholesterol-4-C¹⁴ from the blood across the ovarian membranes into developing yolks. Eggs laid after administration of cholesterol-4-C¹⁴ intravenously contained up to 45.8% of the administered isotope confined completely to the cholesterol fraction of the yolk. Many individual eggs contained from 5–10 μc of cholesterol-4-C¹⁴. The specific radioactivity of yolk cholesterol always had a well defined temporal relationship to the specific radioactivity of cholesterol in the blood. While exact quantitative data are not yet available, the results of these experiments suggest that most, if not all, of the cholesterol in the egg yolk originates from the blood.