vitellus

Now, the human ovum or egg consists of a vitellus or yolk, which is covered by a similar membrane, known as the vitelline.

From What a Young Husband Ought to Know by Sylvanus Stall

The vitellus and the membrane of the egg enlarge with the embryo and absorb by endosmosis the nutritive matter necessary for the latter, contained in the maternal blood.

From The Sexual Question A Scientific, psychological, hygienic and sociological study by Auguste Forel

Yolk, yōk, Yelk, yelk, n. the yellow part of an egg: the vitellus of a seed: wool-oil.—adjs.

From Chambers's Twentieth Century Dictionary (part 4 of 4: S-Z and supplements) by Various

Up to this point the vitellus of the egg, nourished by endosmosis through its membranes, had sufficed for the nutrition of the still very small embryo.

From The Sexual Question A Scientific, psychological, hygienic and sociological study by Auguste Forel

This vitellus or yolk undergoes a series of segmentation or dividings which are known as spontaneous segmentation.

From What a Young Husband Ought to Know by Sylvanus Stall