vitellus

"The ovarian eggs of all animals are identical, small cells with vitellus, germinal vesicle and germinal spot."

From Facts and Arguments for Darwin by Fritz Muller

Thus, in Fishes, the first changes consist in the segmentation of the vitellus and the formation of a germ, processes which are common to all classes of animals.

From Facts and Arguments for Darwin by Fritz Muller

Within the shell the animal portion of the egg is found; which consists of a viscous, colorless liquid called albumen, or the white, and a yellow globular mass called the vitellus, or yolk.

From Donahoe's Magazine, Volume XV, No. 3 Volume XV (Jan 1886-Jul 1886) 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

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