DICT.TW Dictionary Taiwan

 Zo·na n.; pl. Zonae   A zone or band; a layer.
 Zona pellucida. [NL.] Biol. (a) The outer transparent layer, or envelope, of the ovum. It is a more or less elastic membrane with radiating striae, and corresponds to the cell wall of an ordinary cell.  See Ovum, and Illust. of Microscope. (b) The zona radiata.
 Zona radiata [NL.] Biol., a radiately striated membrane situated next the yolk of an ovum, or separated from it by a very delicate membrane only.
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