vitellus

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

"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

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

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

Vit′ellary, Vitell′ine, pertaining to the vitellus, or forming such.—n.

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