Micropyle \Mi"cro*pyle\, n. [Micro- + Gr. ? gate, orifice: cf. F. micropyle.] (Biol.) (a) An opening in the membranes surrounding the ovum, by which nutrition is assisted and the entrance of the spermatozoa permitted. (b) An opening in the outer coat of a seed, through which the fecundating pollen enters the ovule. -- {Mi*crop"y*lar}, a. [1913 Webster]