zona

2 definitions found

zona - Collaborative International Dictionary of English v.0.48 :

  Zona \Zo"na\, n.; pl. Zonae. [L., a girdle. See Zone.]
     A zone or band; a layer.
     [1913 Webster]
  
     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.
        [1913 Webster]

zona - WordNet (r) 2.1 (2005) :

  zona
      n 1: (anatomy) any encircling or beltlike structure [syn:
           zone, zona]