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Medical Term:

lactiferous sinus


a circumscribed spindle-shaped dilation of the lactiferous duct just before it enters the nipple. In nursing mothers, this dilation stores a droplet of milk that is expressed by compression as the infant begins to suckle; this is thought to encourage continual suckling while the let-down reflex ensues.

Synonym(s): sinus lactiferiTA, ampulla lactifera, ampulla of lactiferous duct, ampulla of milk duct, lactiferous ampulla

© Copyright 2017 Wolters Kluwer. All Rights Reserved. Review Date: Sep 19, 2016.