Crooke's granule

[kruks]
n.
  1. One of the lumpy masses of basophilic material in the basophil cells of the anterior lobe of the pituitary gland, associated with Cushing's disease or appearing after the administration of ACTH.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.