alveolar duct

n.
  1. The part of the respiratory passages beyond the respiratory bronchioles, from which the alveolar sacs and alveoli arise.
  2. The smallest of the intralobular ducts in the mammary gland, into which the secretory alveoli open.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.