blastopore

from WordNet (r) 3.0 (2006)

blastopore
    n 1: the opening into the archenteron

from The Collaborative International Dictionary of English v.0.48

Blastopore \Blas"to*pore\, n. [Gr. blasto`s sprout + E. pore.]
   (Biol.)
   The pore or opening leading into the cavity of invagination,
   or archenteron.

   Note: [See Illust. of {Invagination}.] --Balfour.
         [1913 Webster]