At the apex of each basidium a flask-shaped cell, "sterigma" (d), appears.    From Wordnik.com.  [The Elements of Bacteriological Technique A Laboratory Guide for Medical, Dental, and Technical Students. Second Edition Rewritten and Enlarged.] Reference

From each one of these cells of the basidium a long, slender process (sterigma) grows out to the surface of the plant and bears the spore.    From Wordnik.com.  [Studies of American Fungi. Mushrooms, Edible, Poisonous, etc.] Reference