Endocrine control of lipid metabolism in the developing chick embryo

Abstract The effect of hypophysectomy by means of surgical decapitation upon plasma cholesterol levels in the developing chick embryo has been studied from days 8.5 to 18.5 of incubation. Hypophysectomy results in a statistically significant reduction of plasma cholesterol concentrations on days 9.5–10.5 and days 12.5–16.5 of incubation. In pituoprivic chick embryos, plasma cholesterol levels return to normal on days 17.5 and 18.5 of incubation. Normal and hypophysectomized embryos show a depletion of plasma cholesterol concentrations on day 11.5 and highly elevated values on days 16.5–18.5 for the normal embryo, and days 17.5–18.5 for the pituoprivic animal. A single administration of cortisone acetate on days 13.5 to either normal or pituoprivic embryos results in statistically significant elevations of plasma cholesterol concentrations, 1 and 2 days postadministration for the normal embryo, and 1 day postadministration for the pituoprivic animal. The data suggest that the developing chick embryo may well exert hormonal control via the pituitary—adrenal axis over its metabolism and/or transfer of cholesterol.