See Also: egg yolk(medicine)
yolk(dictionary)
yolk(2)(dictionary)
yolk(1)(dictionary)
yolk(medicine)
yolk sac(medicine)
Yolk stalk(medicine)
yolk sac tumour(medicine)
yolk sac carcinoma(medicine)
yolk membrane(medicine)

yolk(1) (iou)



yolk noun1. .

The yellow internal part of a bird's egg, which is surrounded by the white, is rich in protein and fat, and nourishes the developing embryo. Also more fully egg-yolk, yolk of egg. OE.
b. Zoology. The corresponding part in the ovum or larva of all egg-laying vertebrates and many invertebrates. M19.
fig. The best or innermost part of anything; the core. Now Scot. LME.
a. A hard nodule in softer stone, rock, etc. Also, a soft type of coal. Chiefly dial. E18.
b. A rounded opaque thickened part in window-glass; a pane of such glass. Scot. E19.
Comb.: yolk duct = vitelline duct s.v. VITELLINE 2; yolk gland a yolk-secreting gland present in most animals; a vitelline gland; yolk sac (a) a sac containing yolk attached to the embryos of reptiles and birds and the larvae of some fishes; (b) a sac lacking yolk in the early embryo of a mammal.
yolkless adjective L19.