What is "sieve cells"

Sieve \Sieve\, n. [OE. sive, AS. sife; akin to D. zeef, zift, OHG. sib, G. sieb. [root]151a. Cf. Sift.]

1. A utensil for separating the finer and coarser parts of a pulverized or granulated substance from each other. It consist of a vessel, usually shallow, with the bottom perforated, or made of hair, wire, or the like, woven in meshes. ``In a sieve thrown and sifted.''
   --Chaucer.

2. A kind of coarse basket.
   --Simmonds.

   Sieve cells (Bot.), cribriform cells. See under Cribriform.

n. (sieve cell English)