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The Collaborative International Dictionary
Zona radiata

Zona \Zo"na\, n.; pl. Zon[ae]. [L., a girdle. See Zone.] A zone or band; a layer. Zona pellucida. [NL.] (Biol.)

  1. The outer transparent layer, or envelope, of the ovum. It is a more or less elastic membrane with radiating stri[ae], and corresponds to the cell wall of an ordinary cell. See Ovum, and Illust. of Microscope.

  2. 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.

Wiktionary
zona radiata

n. (context biology English) A radiately striated membrane situated next to the yolk of an ovum, or separated from it by a very delicate membrane only.