资料来源 : Webster's Revised Unabridged Dictionary (1913)

Ypsiliform \Yp*sil"i*form\, a. [Gr. ? ? the name of the letter ?
   + -form.] (Biol.)
   Resembling the ? in appearance; -- said of the germinal spot
   in the ripe egg at one of the stages of fecundation.