Note: The ovum is a typical cell, with a cell wall, cell
substance, nucleus, and nucleolus. In man and the
higher animals the cell wall, a vertically striated
membrane, is called the zona pellucida; the cell
contents, the vitellus; the nucleus, the germinal
vesicle; and the nucleolus, the germinal spot. The
diameter of the ripe ovum in man and the domestic
animals varies between 1-200 and 1-120 of an inch.
2. (Arch.) One of the series of egg-shaped ornaments into
which the ovolo is often carved. --Gwilt.