os·ti·ole /ˈɑstiˌol/
  小孔
  Os·ti·ole n.  Bot. (a) The exterior opening of a stomate. See Stomate. (b) Any small orifice.
  ◄ ►
  ostiole
       n : a small pore especially one in the reproductive bodies of
           certain algae and fungi through which spores pass